Smoky Denver rush hour

 As stated earlier, smoke from Nebraska wildfires has traversed across northeastern Colorado and arrived to the Denver metro area.  Fine particulate levels have spiked and visibility has degraded considerably. Fortunately, Denver and surrounding areas will see slow and gradual improvement through this evening. In the meantime, remaining indoors with the doors and windows closed is a good idea. While outside, slow it down a bit.  By later this evening, air quality is expected to improve noticeably.

Denver skyline webcam image Thursday afternoon (https://www.colorado.gov/airquality/live_image.aspx)

Updated expectations for smoke from the 24 Fire

Smoke impacts due to the 24 Fire, located on Fort Carson in south-central Colorado, will continue to be highly variable on Thursday and into Friday. Winds on Thursday have come mainly from the west. Winds are expected to remain breezy and gusty on Thursday afternoon and into the overnight period, however the direction will change as a cooler air mass moves in from the east. This has several implications for fire behavior and smoke impacts.

First, fire behavior may increase once again on Thursday, as was seen on Wednesday, during the warm and dry afternoon. This could increase smoke production, but may also will help with dispersion as atmospheric lift moves much of the smoke vertically away from the surface, and winds help to dissipate concentrations. The west-to-east transport will also limit impacts from smoke in areas of Fremont County, such as Penrose, Florence, and Cañon City.

The second change that we anticipate is a shift in the wind direction this evening, with winds switching to come from the east. This will move smoke in the opposite direction, and toward the above mentioned communities. As the winds shift, the air will cool as the sun goes down, and as cooler air is transported into the region. This will decrease lift in the atmosphere, and smoke may stay closer to ground level. This may create periods of smoke and haze, particularly in areas closest to the fire. Though the shift in wind direction may increase smoke in neighboring communities, breezy and gusty conditions will help to limit overall smoke concentrations.

Map showing the location of the 24 Fire near Cañon City, Colorado, with arrows indicating expected wind directions on Thursday, and Thursday night/Friday morning. Map image from WatchDuty App, 24 Fire information

The third change that is expected is an increase in relative humidity and chances for precipitation. The cool, moist airmass that is incoming will assist in decreasing fire behavior and smoke production. Higher humidity values will remain in the area, and as winds decrease a bit on Friday also, fire behavior is expected to be dampened. 

The take-away message from all of this is: changes are coming, so folks in areas near the 24 Fire should remain prepared to protect their health during any smoke episodes that may be experienced, but also know that these periods of impact are expected to be relatively short lived.

As of this writing (3 pm on 3/26/26) an Air Quality Health Advisory is not anticipated. CDPHE forecasters are watching as all of this unfolds, and will respond with messaging and alerts if they become necessary. As always, our goal is to communicate our expectations so that folks can make informed decisions on what is the right action to take, and when.

Smoke arrives in northeast Colorado, moving towards Denver

Smoke from Nebraska has moved into northeast Colorado. 

Smoke, in gray, is visible on satellite imagery. Image courtesy of RAMMB Cira Slider.

The Ashby Fire and the Minor Fire are burning in Nebraska. Smoke from these fires pushed into northeast Colorado on Thursday. Particulate matter concentrations are elevated for some locations in northeast Colorado, including Fort Morgan, Sterling, and Julesburg. 

Smoke is continuing to move southwest towards the Denver Metro area on Thursday afternoon. Some locations may notice a brief increase in particulate matter, but we do not expect prolonged periods of heavy smoke. 

No major public health impacts are expected at this time, but folks who are particularly sensitive to smoke may want to take steps to protect their health.

24 wildfire intensifying once again

 Hot, dry and windy conditions are once again increasing fire activity at the 24 wildfire located on Ft. Carson army base.  A large smoke plume has developed and is spreading to the north and east of the fire's location near the intersection of the El Paso, Pueblo, and Fremont county lines.  Fortunately, there is quite a bit of lift in the atmosphere that is keeping most of the smoke high up in the sky, though a few brief periods of smoke could move down to the surface near Fountain and southern parts of the Colorado Springs area.  

Some changes will likely arrive after the sun sets.  As atmospheric mixing decreases with cooler temperatures, smoke will start to hug the surface of the earth and potentially impact nearby communities.  We also anticipate the wind to shift which could send smoke in various directions. One direction it could move is to the south and southwest which could impact parts of Fremont County, including Cañon City, Florence and Penrose. This is most likely to occur at some point between 8pm and midnight Wednesday evening. Fortunately, any smoke that infiltrates these areas should be relatively brief (perhaps an hour or two), so significant health impacts are not anticipated at this time. However, it is always a good idea to take steps to protect your health when smoke is present in your neighborhood, including remaining indoors with the doors and windows closed until the smoke clears.

A cold front will be arriving Thursday night which could bring some more impactful changes to the air quality in Fremont County. A wind shift may push smoke into those same Fremont County locations discussed above for several hours Thursday night. Wet weather likely arrives Friday morning which would clear out the smoke and improve the air quality. We will monitor the situation closely and issue an advisory for Thursday night, if necessary.

View of the 24 wildfire from Fremont County Airport to the east of Cañon City (weathercams.faa.gov)

Update on 24 Fire in Fremont, El Paso, Pueblo Counties

The 24 Fire continues to burn near the Fremont/El Paso/Pueblo County intersection. The fire is currently at 7,404 acres with 24% containment. Portions of the fire remain active at times, producing smoke that may cause intermittent impacts in areas near the fire. Good atmospheric mixing and ventilation will help to lift and disperse smoke during daytime hours. However, warm and dry conditions are also expected, with a Red Flag Warning in place in areas near the fire. Breezy and gusty winds may be present on Wednesday and Thursday, and may increase fire behavior and smoke production. Additionally, periods of moderate to heavy smoke may be encountered during the overnight hours in locations adjacent to the most active portions of the fire.

Folks in areas near this incident are encouraged to take precautionary preparations to limit impacts from smoke, if conditions worsen quickly.

Over the last several days, periodic impacts from moderate to heavy smoke have been observed, but overall have not met conditions that warrant the issuance of a widespread or long-lasting Air Quality Health Advisory. CDPHE meteorologists continue to watch this incident closely, and will respond with advisories and alerts if necessary.

Wildfire on Ft. Carson remains active

 The 24 wildfire continues to actively burn on the Ft. Carson US Army post located near the intersection of the El Paso, Fremont, and Pueblo County lines.  It is now approaching 2000 acres in size with the recent, hot, dry and windy conditions.  

The good news is that the majority of the smoke has been lofting well into the sky during the afternoons and evenings for the past several days. Additionally, overnight smoke (which is generally the heaviest and creates the biggest health concerns) has remained away from the local communities.

One thing we are watching closely is the anticipated wind shift that will be arriving on Sunday.  This could push smoke into new directions, however it still appears that most of the nearby towns will be spared from the worst of the smoke impacts.  Despite this, there remains the possibility for brief periods of heavy smoke in communities to the south of the fire such as Penrose and Florence.  Even areas a bit further from the fire, including Pueblo and Cañon City, could see some smoke from time to time.  

Although an advisory is not anticipated at this time, residents in the area can get prepared to protect their health from wildfire smoke by visiting CDPHE's Wildfire smoke and health webpage. It could very well be a long and impactful wildfire season in Colorado, so being prepared now could certainly come in handy later this spring and summer.

Heat signature of the 24 wildfire from Band 7 shortwave satellite imagery on Saturday evening.

Smoke visible from Fremont County Fire

The 24 Fire in Fremont County sparked on Wednesday, March 18. A new plume of smoke appeared Thursday afternoon, pushing southeast. Hazy skies are likely this afternoon, particularly in Pueblo County. Residents in northeastern Fremont and southwestern El Paso counties also may notice haze.

A plume of smoke is visible on satellite imagery. Image courtesy of RAMMB Cira Slider.

Currently, atmospheric mixing is good, allowing smoke to mix vertically into the atmosphere, rather than sinking to the surface. Because of this, no major public health impacts are expected at this time. CDPHE will continue to monitor the situation and issue an Air Quality Health Advisory if necessary. 

Additionally, if you are located near the fire, you may consider taking steps to protect your health. 

For real-time air quality conditions near you, check Colorado's Monitoring Network or your nearest PurpleAir Sensor.

Lingering smoke in southeastern Colorado

 Although many parts of eastern Colorado have seen air quality improvement over the past several hours, some areas continue to deal with lingering smoke from wildfires in Nebraska.  The atmosphere has been a bit more stubborn in southeastern Colorado, particularly along the Arkansas River Valley from Pueblo eastward through La Junta to Lamar.  Therefore, the Air Quality Health Advisory for Wildfire Smoke has been extended through 9am Saturday morning.  Continue to limit activities that require physical exertion in this part of Colorado, and also reduce your time outdoors if possible.  The smoke should gradually decrease as we head into the start of the weekend.

A hazy sky over Kit Carson County Airport in Burlington (weathercams.faa.gov)

Friday morning surprise smoke across eastern Colorado

 Smoke from a couple of large wildfires in Nebraska has spread into eastern Colorado on easterly winds.  High levels of fine particulates have been reported Friday morning along the Platte River Valley from Julesburg westward into Sterling, Ft. Morgan, Greeley, and even parts of Ft. Collins along the foothills.  Smoke has also pushed into the east-central and southeastern plains. with smoke concentrating along the Arkansas River Valley from Lamar westward to La Junta and Rocky Ford.

The good news regarding air quality is that the smoke should rapidly dissipate during the morning hours across northeastern Colorado as gusty westerly winds develop.  These winds will improve atmospheric mixing and smoke should decrease quickly.  Smoke may linger a bit longer for areas further south, as it may not be until this afternoon until we see improvement along the Arkansas River Valley.  Due to the high levels of particle pollution with this smoke, an Air Quality Health Advisory for Wildfire Smoke has been issued.

Be sure to protect your health while smoke is present in your neighborhood.  Remaining indoors and avoiding physical exertion are a good start.  You can find more way to protect your health at CDPHE's Wildfire smoke and health webpage.

Heavy smoke Friday morning at Ft. Morgan Municipal Airport (weathercams.faa.gov)

Prescribed Burning Operations Planned at the Rocky Mountain Arsenal

Several prescribed burns are planned over the coming days and weeks at the Rocky Mountain Arsenal. Operations are intended to begin as early as Thursday March 5th. Smoke from prescribed burns may be visible from the Denver Metro area, especially in northern Denver and near the Rocky Mountain Arsenal.

For additional information on burning operations, please refer to the Prescribed Fire Map using the tab above. Also, you can find information about how smoke may affect your health on the CDPHE webpage: Wood smoke and your health.

Pile burning season appears like it will finally arrive to Colorado later this week

 

A pile burn in the Grand Mesa National Forest, November 2020

Two factors have really delayed pile burning in Colorado as we approach the end of 2025.  First, the federal government shutdown has not allowed agencies to work on these types of projects.  Second, the weather has definitely not been cooperative.  Pile burning really ramps up when the snow starts flying.  As Coloradoans are well aware, snow has been lacking in a big way this autumn.  

Fortunately, it appears that both of those factors are changing.  With federal agencies getting back to work and a big weather pattern change on the way, we should start to see a significant increase in pile burning operations.

We will provide occasional updates on pile burning projects, especially the bigger burns that will be in close vicinity to communities that could be impacted by the smoke.  You can check the status of scheduled burn operations at the "Prescribed fire map" tab above.  Also be sure to to check out our Woodsmoke and your health webpage if there will be prescribed fires taking place near your area.

There are also many other great resources to get prescribed fire information from individual national forests.  The Arapaho & Roosevelt National Forest provides information including an interactive map. Also check out the Medicine Bow-Routt National Forest webpage for burn information in that part of Colorado.

Update on Prescribed Burning Operations This Week

As mentioned in a post yesterday, two prescribed burns were scheduled to take place along the Front Range this week. This post serves as an update on those planned operations.

The Mathews Pasture, Spruce Meadows project is located in southern Douglas County will take place today, Wednesday, November 12. Smoke from this operation will be visible at times along I-25 between Larkspur and Monument, as well as in areas near the burn site. Please refer to the news story provided by Douglas County for additional information. To see the location of the burn, please refer to previous blog post or the Prescribed Fire Map tab above.

Planned operations for prescribed burning in Boulder County have been postponed, and will not take place this week. Once this operation has been rescheduled, we will provide updated information and expectations.

Prescribed Burning Operations Planned This Week

Two projects for prescribed burning operations are planned to take place along the Front Range this week.

The Mathews Pasture, Spruce Meadows project is located in southern Douglas County, between Larkspur and Monument. These operations are planned to take place on Wednesday November, 12. Smoke from this burn will be visible along I-25 and from locations in this area. Please see the map in the image below for the location of this burn, or consult the Prescribed Fire Map by clicking on the tab above.

Map of location of the Mathews Pasture, Spruce Meadows prescribed burning operation.

The Flatirons Vista project is located south of Boulder, near Eldorado Springs, and is currently expected to take place on Thursday, November, 13. Planning and resource assembly are underway for this operation, taking great care to ensure public safety and minimize any impacts to local air quality. Smoke from this operation will be visible from many locations along the Front Range including Boulder, Broomfield, and the surrounding communities.

As with the above mentioned project, please see the map in the image below for the location of this burn, or consult the Prescribed Fire Map by clicking on the tab above.

Map of location of the Flatirons Vista prescribed burning operation.

The ignition for both operations has not yet been confirmed, and will be based on adequate staffing resources and favorable weather conditions. Due to the visibility of both projects CDPHE/APCD and the agencies conducting these operations want to draw public awareness to these plans.

No significant public health impacts are expected from either operation, however light to moderate smoke is possible in the immediate vicinity of both prescribed burns. If you are sensitive to smoke (fine particulates), please consider taking precautions to protect your health in these areas as these operations take place.

Prescribed burning operations taking place in Boulder County

 A test burn for a prescribed burning operation will take place in Boulder County on Wednesday, just west of Lyons. The location of this burn and additional information can be found on the Prescribed Fire Map, accessed through the tab at the top of this page. Smoke from this operation will be visible on Wednesday afternoon in areas near the burn site, as well as from locations along the Front Range. 

No public health impacts are expected from this operation, however light to moderate concentrations of smoke may be present in areas in the immediate vicinity, possibly including the town of Lyons.

If you are sensitive to smoke, please consult the health recommendations found via the Health Information tab above.

Elevated levels of smoke linger in areas near prescribed burns in southwestern Colorado

PurpleAir particulate monitors show that localized areas of smoke have continued to linger during overnight and early morning hours, due to prescribed fire activity that took place this week.

Screenshot from PurpleAir showing elevated levels of smoke in localized areas near Pagosa Springs, CO on Saturday morning. Raw PM2.5 data are corrected with US EPA conversion factor, using 1 hour timeseries, valid at 8:21 am on September 20, 2025.

Over the last several days, we have seen higher particulate numbers early in the day, with concentrations decreasing during the afternoon and evening as daytime mixing of the atmosphere and smoke dispersion take place. This pattern may continue until fuels have stopped smoldering. Similar smoke behavior may also be observed in other areas where prescribed burning has recently been performed.

We urge anyone in areas that are affected by smoke, especially those who are sensitive to particulate pollution, to remain aware of conditions and protect your health through whichever actions are most appropriate for you.

Prescribed burns in southern Colorado

 A 370-acre prescribed fire is scheduled for today in San Miguel County. This burn is located northeast of Dove Creek. Smoke may be visible in the area on Friday, but no major public health impacts are expected. If you are near the burn and sensitive to smoke, it's a good idea to protect your health. 

Location of the burn in relation to Dove Creek, Colorado. Image courtesy of Google Maps.

Also, smoke is lingering near Pagosa Springs from another prescribed fire, which took place on Thursday. This smoke may continue Friday morning, but should begin to clear by the afternoon.

Purple Air sensors near Pagosa Springs show smoke is lingering Friday morning. Sensors show 1-hr Raw PM 2.5 data, current as of 11:15 AM.

Visit our Prescribed Fire Map page or the Prescribed Fire Information tab above for more information on prescribed burns.

Large prescribed burn taking place on Thursday in SW Colorado

 A 400 acre prescribed burn is planned to take place today near Pagosa Springs. The Brockover Devil Creek Rx project is located north of Highway 160, in between Pagosa Springs and Chimney Rock. Smoke may be visible in this area as these operations take place. Please see the Prescribed Fire tab above for more information.

Location of the prescribed burning operations is shown on a map, courtesy of the National Weather Service spot forecast Monitor page.

While no significant public health impacts are expected from this operation, folks in this area who are sensitive to smoke may choose to take actions to prevent health impacts.

Some smoke improvements for Sunday

In northwestern and north-central Colorado, the smoke has mostly moved out. An Air Quality Health Advisory was in effect Saturday, but will expire at 9 am today. PurpleAir sensors across the northwest have shown a dramatic reduction in Particulate Matter concentrations as of this morning. Particulate matter concentrations are expected to be in the Good to Moderate range on Sunday and Monday.

On the Front Range and eastern Plains, smoke is lingering this morning. But changes are on the way. Unsettled weather, shifting winds, and scattered showers will help to clear out the lingering smoke. Particulate Matter concentrations are expected to drop throughout the day on Sunday.

CDPHE does not anticipate issuing any Air Quality Health Advisories at this time. For the most up-to-date air quality information, visit CDPHE's Monitoring Website or PurpleAir.

Lingering smoke on Saturday

 Smoke began moving into northwest Colorado on Friday afternoon. Northwestern and north-central Colorado are waking up to smoky conditions this weekend. This smoke is expected to continue through Sunday morning. 

An Air Quality Health Advisory remains in effect for northwestern and north-central Colorado until Sunday morning. This advisory was issued on Friday afternoon for Moffat, Routt, Jackson, and Grand Counties. As of Saturday morning, this advisory has been updated to include three more counties: Clear Creek, Gilpin, and Summit. Moderate to heavy smoke is possible throughout the advisory area on Saturday and Sunday. 

Changes are coming on Sunday. Today, upper-level winds are coming from the northwest, where the smoke is heavy. On Sunday, these upper-level winds are expected to shift to westerly (coming from the west), where the air is cleaner. A shift to westerly winds would bring cleaner air into northwest Colorado. Particulate Matter concentrations are expected to drop throughout the day on Sunday. Until then, in the advisory area, it's a good idea to take steps to protect your health. For the latest air quality information, visit CDPHE's monitoring website or PurpleAir.

Smoke moving into northwest Colorado

 Smoke has been impacting eastern Colorado for most of this week. Today, smoke has begun moving into counties west of the Divide. We'll break it down, starting in the northwest corner of the state. 

Northwestern Colorado is experiencing the heaviest smoke. Purple Air sensors show that particulate matter concentrations began rising on Friday afternoon. This smoke is expected to linger Friday night into early Saturday morning. An Air Quality Health Advisory is in effect for Moffat, Routt, Jackson, and Grand Counties through Saturday morning.

Further south, in Eagle, Summit, Gilpin, and Clear Creek Counties, smoke is less intense. There will be noticeable haze along I-70 on Friday afternoon and Saturday morning.

Purple Air Sensors show that the heaviest smoke is in northwestern Colorado.

On the Front Range, the heaviest period of smoke is behind us. Particulate Matter concentrations are expected to be in the Moderate category throughout the weekend.

Air quality is expected to improve next week, as upper-level winds shift and smoke clears out.

Wildfire smoke continues to increase

Smoke has arrived to the northeastern plains of Colorado.  Moderate to heavy smoke has been observed across the northeastern corner of the state.  Fortunately, as we stated in our last post, we don't expect this smoke to be around for an extended period of time.  A cold front later on this evening should usher in some cleaner air overnight and air quality should be improved in places like Julesburg, Sterling, Ft. Morgan, and Akron by Friday morning.  In the meantime, reducing exertion is probably a good idea for the remainder of today.  This is especially true if you suffer from heart or lung ailments.

Hazy skies and poor visibility in Akron, Colorado Thursday afternoon.  Webcam image is courtesy of Viaero Wireless Weather Cameras

Meanwhile, smoke is also increasing further west along the northern Front Range urban corridor.  Fine particle concentrations are increasing in Denver, Boulder, Longmont, Ft. Collins, Greeley, and other areas along and near Interstate 25.  Combined with typical urban pollution, both ozone and fine particulate concentrations are inching towards the Unhealthy for Sensitive Groups category.  Therefore, an Action Day for Multiple Pollutants has been issued for the northern Front Range. We anticipate both ozone and fine particulates to be elevated through this evening, so avoiding prolonged or heavy exertion is recommended through late tonight. By tomorrow (Friday), ozone will likely decrease somewhat with cooler air rushing in behind the cold front.  However, fine particle concentrations could remain elevated for a longer period of time.  Health impacts from prolonged exposure to wildfire smoke can linger even after the air quality improves, so it may be a good idea to plan on reducing exertion through at least tomorrow afternoon.

Haze over the Denver skyline from the Colorado Air Pollution Control Division web camera

We are also closely monitoring other parts of Colorado for increasing wildfire smoke.  East-central and southeastern parts of the state, including Burlington, Lamar, Colorado Springs, and Pueblo could see an increase in particle pollution overnight tonight and continue into the Friday morning commute.  The same can be said for northwestern parts of the state with the possibility for a larger smoke intrusion tomorrow afternoon in places like Steamboat Springs and Granby. More information to follow as this situation continues to evolve.

Smoke arriving from out-of-state on Thursday

Smoke from fires in areas upwind from Colorado is now making its way toward, and into Colorado. Surface concentrations are currently in the Moderate category in most areas of Colorado, however the numbers have climbed in areas just to our north and east throughout the morning, and the this trend is expected to be seen in eastern Colorado as the day progresses.

Satellite image of the western United States shows a large plume of smoke across many states, reaching from the Pacific Northwest into Montana, Wyoming, and Nebraska. This smoke will make its way into Colorado on Thursday afternoon (smoke plume and likely path of travel indicated by red arrow). Image courtesy of RAMMB/CIRA.

Increases in particulate concentrations will be seen first in the far northeastern portions of the state as surface smoke moves in, and daytime mixing of the atmosphere draws smoke aloft down to ground-level. Locations such as Sterling and Fort Morgan will be the first to notice this change.

Winds out of the north-northeast will then push the smoke further to the south and west. This will likely produce hazy skies and elevated particulate concentrations in many areas of eastern Colorado, including the Front Range.

Currently we do not expect that any Air Quality Health Advisories or Action Days will be necessary. Models and observations both indicate that the smoke plume is relatively concentrated, meaning that once the densest portion of the plume moves through, concentrations are likely to decrease once again. However in the short-term, we expect particulate levels to increase on Thursday afternoon and evening before relief arrives on Friday. If conditions worsen further than we expect them to, we will be watching closely and will issue Advisories as needed.

Folks who are sensitive to smoke and particulate pollution should begin taking steps to avoid exposure and reduce potential health impacts now. Helpful tips and actions can be found on our Smoke and Health page.

Stay informed by checking in here and on CDPHE's webpage for information regarding advisories. You can also see the location of the smoke plume and surface observations at EPA's Fire and Smoke Map.

More smoke arriving later this week

 Many large wildfires are burning in the Pacific Northwest and British Columbia. Smoke from these fires could begin to impact northeastern Colorado by Thursday afternoon.

A heavy blanket of smoke is visible over western Canada and the northwestern United States. This smoke could move into Colorado by Thursday afternoon. Image courtesy of CIRA-RAMMB.

In the Pacific Northwest, particulate matter is in the Unhealthy for Sensitive Groups to Unhealthy Range today. Some smoke has made its way into Colorado, but particulate matter is in the Good to Moderate range today. Tomorrow, particulate matter could increase as the smoke to our north begins to push south.

By Thursday afternoon, the wind will begin to increase. Northerly winds will push smoke into northeastern Colorado. Smoke will hit Fort Collins, Greeley, Fort Morgan, Sterling, and Julesburg first. Then, it will continue to move south, hitting Boulder, Denver, and Colorado Springs. Particulate Matter concentrations will increase as the smoke moves in. If you are sensitive to smoke, take steps to protect your health on Thursday.

Visit the Idaho Smoke Blog or the Washington Smoke Blog for more information on smoke in the Pacific Northwest.

CDPHE is monitoring the situation and will issue an Air Quality Health Advisory if necessary.

Smoke heading towards Colorado

The fires in western Colorado have calmed down, but more smoke may be in the picture today.

Activity on the Derby Fire and Stoner Mesa Fire has slowed significantly. We do not expect heavy smoke from either of these fires today.

However, multiple fires are burning in the Pacific Northwest and Canada. This smoke may move into Colorado by Tuesday afternoon. 

On visible satellite imagery, smoke (gray) is visible over the Pacific Northwest and Canada. This smoke could move into Colorado on Tuesday afternoon.

How much smoke are we talking? In eastern Colorado, there may be a noticeable haze this afternoon. Particulate Matter is expected to reach the Moderate level in locations along the Front Range and northeastern plains, including Fort Collins, Greeley, Sterling, Julesburg, Boulder, Denver, and Colorado Springs. If you are particularly sensitive to smoke, consider taking it easy today. 

Smoke may also impact areas west of the Continental Divide. Locations in north-central Colorado, including Steamboat Springs, may see haze and increased particulate matter concentrations this afternoon.

The current weather pattern is expected to continue for the rest of this week. Continued northerly surface winds could bring more smoke into Colorado later this week. We will provide updates as necessary.

Currently, no Air Quality Health Advisories are in effect. CDPHE is monitoring the situation and will issue an advisory if conditions worsen.

Increasing wet weather

Scattered showers and thunderstorms are expected across large portions of western Colorado on Sunday, possibly including the Stoner Mesa fire and the Derby fire sites.   Air quality health advisories will remain in effect for areas close to those two fires and smoke levels remain elevated Sunday morning.  However we are cautiously optimistic that there will be a general improvement in air quality over the next 24 hours due to less fire activity from cloud cover, and perhaps wetting rains from the shower and thunderstorm activity.

Geocolor satellite image of widespread cloud cover over western Colorado Sunday morning.  Image courtesy of Cooperative Institute for Research in the Atmosphere at Colorado State University

No major changes for the time being

 Air quality conditions Saturday morning look very similar to what they were 24 hours ago (see yesterday's blog post below).  Heavy smoke is mainly found in close vicinity to the Stoner Mesa fire in southwestern Colorado and the Derby fire in central Colorado.  Air quality health advisories will continue for these areas through at least Sunday morning.

There will be a scattering of showers and thunderstorms near the two fires Saturday afternoon, but wetting rains appear more likely on Sunday. We are hopeful this will continue the gradual improvement in air quality as we head into the early part of the workweek.

Relief on the way?

 Another day of localized heavy smoke near the Stoner Mesa fire and the Derby fire. Much like yesterday, the heaviest smoke will likely remain in close vicinity to the fires.  For Stoner Mesa, parts of western Eagle and eastern Garfield Counties remain in the advisory area. The Sweetwater Lake area along with Colorado River Road between Dotsero and Burns will receive heavy smoke during the overnight and early mornings, with improving air quality during the afternoons.  Yesterday afternoon we did see some downwind impacts in places like Basalt and Aspen.  That possibility exists again today, but with showers and thunderstorms possible near the fire there could be gusty, erratic winds that could send smoke in any direction. Regardless, we don't anticipate smoke to travel very far from the fire site today.

At the Stoner Mesa fire, there has been very heavy smoke along Highway 145 between Dolores and Rico.  The Stoner area has been especially hard hit, so if you are camping or reside in this area please take action to protect your health.  You can even create a clean air space in your RV by constructing a DIY air cleaner.

The forecast appears encouraging for western Colorado over the next few days as a surge of monsoonal moisture should help decrease fire activity and smoke production.  In the meantime, we'll continue to monitor the smoke and issue advisories if necessary. 

Smoky conditions will continue Thursday for parts of central and southwestern Colorado

 The Derby fire is located in central Colorado approximately 13 miles north of Dotsero and remains quite active Thursday morning. CDPHE issued an air quality health advisory yesterday for four counties due to smoke moving to the south and east of the fire. One concern was that smoke would be trapped within the narrow mountain valleys in this area, but fortunately many parts of the advisory area only have light to moderate smoke Thursday morning.  Therefore, the advisory for today will be smaller with the removal of Summit, Lake, and Pitkin Counties.  Eastern parts of Eagle County also look OK, but the advisory today will continue for western Eagle County with the addition of a small part of eastern Garfield County. Below is a map with areas most likely to receive periods of heavy smoke through Friday morning.

The area of concern for heavy smoke Thursday morning through Friday morning near the Derby fire.

 Heavy morning smoke can be expected in the vicinity of Sweetwater Lake in eastern Garfield County, along with locations on Colorado River Road between Dotsero and Burns. Meanwhile, the stretch of Interstate 70 between Dotsero and Eagle (including Gypsum) are also included in today's advisory.

A new data point has revealed that heavy smoke is still impacting parts of southeastern Dolores and northeastern Montezuma Counties in southwestern Colorado from the Stoner Mesa fire.  Campgrounds and residences along Highway 145 between Dolores and Rico, especially in the Stoner area, will experience heavy smoke Thursday morning with likely some improvement during the afternoon hours.  Smoke will likely return again to this area late Thursday night and early Friday morning.

The area of concern for heavy smoke Thursday morning through Friday morning near the Stoner Mesa fire.

Looking ahead, there is some promising news in the long-range forecast for the Western Slope.  An increase in monsoonal moisture is anticipated starting on Friday and continuing into the weekend.  This should help to decrease fire activity and smoke production somewhat, but we will also need to monitor for potential new fire starts from lightning strikes.

Air Quality Advisory issued downwind of the Derby wildfire

 The Derby fire has grown significantly over the past 24 hours and is producing very large amounts of smoke Wednesday afternoon.  The transport winds over the fire are not particularly strong, but they are pushing smoke to the south and east.  This has resulted in increased fine particulate (PM2.5) concentrations and worsening air quality across large swaths of Eagle, Summit, Pitkin, and Lake Counties.  An Air Quality Health Advisory for Wildfire Smoke has been issued for this area through at least 9am Thursday morning.   

The numerous communities along that long stretch of Interstate 70 between Silverthorne and Dotsero will be impacted by reduced visibility and periods of moderate to heavy smoke. Also expect increasing smoke Wednesday evening in places like Aspen and Leadville.  So please drive safely in areas where visibility is obscured. And as always, we remind you to please take action to protect your health. The valleys in this part of Colorado are notorious for trapping smoke, so this could very well be an issue through the Thursday morning commute.

GeoColor image of the Derby fire and heavy smoke located in northwestern Eagle County. Image courtesy of Cooperative Institute for Research in the Atmosphere at Colorado State University

Derby Fire burning in Eagle County

A new fire has sparked in northern Eagle County- the Derby Fire. 

Smoke from this fire is visible on satellite and is spreading south and east. Smoke may be visible Wednesday morning along the I-70 corridor, including Dotsero, Gypsum, Eagle, and Edwards. Throughout the day, there may be brief periods of moderate smoke. Particulate matter concentrations may begin to increase Wednesday afternoon, but will likely remain in the Moderate category.

No major public health impacts are expected at this time, and there is no Air Quality Health Advisory in effect. CDPHE is monitoring the situation and will issue an advisory if conditions change. Find the latest air quality information on PurpleAir or on CDPHE's monitoring website.

View of the Derby Fire on August 18. Image courtesy of InciWeb.

The Lee Fire, Stoner Mesa Fire, and Turner Gulch Fire are still burning in western Colorado. Locations near these fires may see periods of moderate smoke today. But unlike last week, widespread, heavy smoke is not expected from these fires today.

Areas of morning smoke near the fires on Sunday

 Air quality monitoring and satellite imagery reveal some smoke located in close vicinity to West Slope wildfires Sunday morning.  Smoke has drained overnight from the Stoner Mesa fire extending southwestward into Montezuma County with smoke being reported in Dolores, Cortez and Towaoc.  Fortunately, this smoke should decrease as progress through the morning and no advisory is necessary at this time.  If you do want to spend time outdoors in this part of Colorado, waiting until this afternoon would probably be the best choice for your personal health. The same holds true for those located close to the Crosho fire or Lee fire located in Rio Blanco County in northwestern Colorado.

The weather is steadily drying out across western Colorado so the wildfires may start getting active again Sunday afternoon.  We will keep you posted if any air quality advisories are necessary.

A hazy early morning at Cortez Municipal Airport.  Image courtesy of the Federal Aviation Administration

Air quality improves for Saturday

Today is the day- finally, no air quality health advisories are in effect!

The Lee Fire, Crosho Fire, and Stoner Mesa Fire are still burning. On Friday, western Colorado experienced rain and high relative humidity. This limited the fires' growth and resulted in less smoke from these fires. Today, Coloradans are waking up to cleaner air. 

We do not expect Particulate Matter concentrations to reach the Unhealthy for Sensitive Groups (orange) category today. There still may be a noticeable haze today. In areas near the fires, there may be periods of moderate smoke. If you are very sensitive to smoke, you can take steps to protect your health. But know that today will be an improvement from earlier this week.

Particulate matter concentrations are in the Good to Moderate range statewide.

PurpleAir Sensors are showing Good to Moderate air quality Saturday morning. Image courtesy of PurpleAir.

CDPHE is still monitoring these fires and will issue advisories as needed. 

Significant improvement in air quality for many areas

 Widespread cloud cover, higher relative humidity, and even a few showers and thunderstorms resulted in a decrease in fire activity yesterday on the Western Slope.  The result is lower smoke levels for most of Colorado Friday morning.  More good news -- moisture continues to surge into western Colorado.  This should moderate fire activity again for today and limit smoke production.

Friday morning satellite image of moisture surging into the Four Corners area. Image courtesy of Cooperative Institute for Research in the Atmosphere at Colorado State University

With less fire activity expected today, smoke impacts should be more localized.  We have decreased the size of both air quality health advisories in western Colorado.  Heavier smoke impacts should remain in close vicinity to the Lee fire, Crosho fire, and Stoner Mesa fire.  For the Lee and Crosho fires, expect heavier smoke to remain in rural areas of Rio Blanco county close to the fires, along with southern Routt County in the Phippsburg area.  This smoke will likely be heaviest during the early morning hours, so outdoor plans may be more appropriate during the afternoons.  It is a similar story on the Stoner Mesa fire where unhealthier smoke levels will mainly be confined to eastern Dolores and northern Montezuma Counties, including the communities of Rico and Dolores.

Looking ahead, the weather will likely gradually dry out again over the course of the weekend, so if you are in an area with improved air quality today you may want to take advantage of it.

Wildfire smoke remains in the forecast for many

 Most of Colorado is experiencing at least moderate levels of smoke Thursday morning.  The heaviest smoke can be found in close vicinity to wildfires in western parts of the state, while the Colorado River Valley between Gypsum and Vail is also seeing highly elevated levels of fine particulate matter.

Wildfire smoke producing moderate (yellow) to unhealthy for sensitive groups (orange) levels of fine particulate matter Thursday morning.  Map and data courtesy of the EPA's Fire and Smoke Map

Unfortunately Red Flag Warnings blanket the western half of Colorado on Thursday.  The primary threat will be dry thunderstorms which could initiate new fires and perhaps enhance current fires due to gusty winds.  CDPHE meteorologists will be closely monitoring for new wildfire starts throughout the day.

Counties shaded in pink are under a Red Flag Warning on Thursday.  Image courtesy of the National Weather Service GIS Viewer

The Air Quality Health Advisories that were in effect yesterday will be extended through at least Friday morning, but there will be some changes.  We do anticipate the Lee fire and the Crosho fire to remain active today and send smoke downwind to the northeast.  This will increase the potential for smoke in places like Steamboat Springs and Walden Thursday afternoon.  The highest smoke impacts will remain for areas along and north of Interstate 70 in northwestern and north-central Colorado.  Meanwhile, we do anticipate some gradual improvement for areas a bit further to the south and west, including Grand Junction, Delta, Montrose and Gunnison.  Those areas have been removed from today's advisory, but locals should still take it a little slower than usual as the recent exposure to smoke could have some lingering health impacts.

Meanwhile in southwestern Colorado, the Stoner Mesa fire continues to burn in eastern Dolores County.  This area is also under a Red Flag Warning and could see some growth today, especially if it is impacted by gusty outflow winds from dry thunderstorms.  One small piece of good news is that the transport winds are not particularly strong today in southwestern Colorado, so we are not expecting smoke to move very far away from the fire.  Therefore, air quality should improve somewhat in places like Telluride, Ouray and Silverton.  The flip side is that we are seeing increasing amounts of drainage smoke.  This is the smoke that flows downhill during the early morning hours and generally is at its worst right around the morning rush hour. Cortez and Durango have both seen an uptick in smoke over the past 24 hours.  Though these areas should see some improvement Thursday afternoon once the atmosphere heats up, smoke could very well return late Thursday night into early Friday morning.

Surface smoke at Cortez Municipal Airport Thursday morning. Image courtesy of the Federal Aviation Administration

Below is a map of Colorado showing active Air Quality Health Advisories.  With the rapidly changing atmospheric and wildfire conditions, we urge you to remain up-to-date on current advisories by visiting our website and signing up for email alerts.

Current Air Quality Health Advisories, by county.  Map from Colorado Department of Public Health and Environment, Air Pollution Control Division website