Smoke from out of state affecting western Colorado

The Slough Canyon Fire in eastern Utah was very active on Saturday and produced significant amounts of smoke. Initial expectations were that the majority of smoke would be carried to the north-northeast and have little effect on Colorado air quality. On Sunday morning, observations show that smoke moved into the Grand Valley and bumped PM2.5 (smoke) concentrations into the low Moderate category in Grand Junction.

Map showing the location of the Slough Canyon Fire in eastern Utah, northwest of Grand Junction, CO. Yellow dots show Moderate air quality on particulate monitors in areas of the Grand Valley. Image courtesy of EPA's Fire and Smoke Map.

Smoke may lift as atmospheric mixing increases during daytime hours, and concentrations may decrease. Smoke may also be transported to other areas of Colorado. Smoke is expected to remain pretty light, only reaching the Moderate category in the current outlook period. Hazy skies and light concentrations of smoke may be seen in Mesa, Rio Blanco, and Moffat Counties on Sunday and Monday.

We will keep a close eye on this fire and revise expectations if the situation changes.

Wildfire smoke in Colorado expected to remain minimal

In our last post we noted a possibility that smoke from out-of-state wildfires may be moving into our region this evening. We want to provide an updated outlook for this scenario. Current modeling shows that a ridge of high pressure is building in the southwestern U.S. This will route the upper level winds that are carrying the majority of smoke to our north. While we cannot rule out a bit of haze, particularly in areas of northeastern Colorado, we expect very little smoke to reach the surface. This trend appears to last at least into this weekend.

Until all fires are contained and smoke production ceases, the potential for smoke to again invade our area will remain. However for now this is not an immediate concern.

Colorado all clear at the moment

No new developments with wildfire smoke across Colorado as the workweek gets started. Heavy smoke remains bottled up across the Pacific Northwest while ample moisture in Colorado is stopping any development or intensification of local wildfires. There is a possibility for some out-of-state smoke to move into northeastern Colorado (including the Denver/Boulder/Ft. Collins urban corridor) late Wednesday into early Thursday. However, still plenty of uncertainty with that scenario so we will continue to monitor the situation over the next few days.

Smoke remaining minimal in Colorado, for now

We have seen improved air quality here in Colorado due to decreased fire behavior from in-state fires, and less transport of smoke from out-of-state. We are quite pleased to have this break from the smoke. However, we want to remain aware of the conditions that could affect us, even if this is not expected to happen immediately.

Wildfires continue to burn in the Pacific Northwest, with smoke and poor air quality present in many areas of  Washington, Oregon, and Idaho. This smoke is being carried eastward, and much of it is not reaching the surface.

Map of the western United States showing Good to Moderate air quality in many areas of the Rocky Mountains. Poor air quality due to smoke continues in the northwestern U.S. Image courtesy of EPA's Fire and Smoke Map.

Weather models indicate that the current pattern that is keeping smoke to the north of Colorado will continue through the weekend and into next week. There are some indications that the pattern may shift by mid-to-late next week, and smoke may return to our area. It is too soon to put much confidence into this possibility, but we always seek to be aware, and keep you informed.

We will continue to monitor smoke conditions with an eye on the potential for these changes in Colorado. We will update information here as things develop.

Smoke gradually decreasing in most areas

Some promising trends are in the forecast as we close out the weekend. As stated in yesterday's post (see below), the upper level winds are transporting the heaviest smoke to the north of Colorado. Additionally, afternoon showers and thunderstorms are starting to increase with monsoonal moisture being pumped into the state. This combination will result in particle pollution levels continuing to gradually decrease. Currently, a light haze hangs over most of the state with moderate levels of particle pollution (PM2.5).

Air quality monitors showing moderate levels of particle pollution throughout Colorado. Image and data courtesy of EPA's Fire and Smoke Map

There are a few areas that may receive a little heavier smoke from time to time. Local fires such as the Gold Mountain fire and the Elk fire still have hot spots and will produce locally heavy smoke at times. The I-25 urban corridor near Denver, Boulder, and Ft. Collins is still under an advisory for both ozone and smoke until 4pm Sunday, but smoke levels are also decreasing in this area. 

Two other areas could also get some quick hits of heavier smoke from upwind fires over the next day or two. These include the northeastern plains of Colorado and parts of far west-central and southwestern Colorado. This is something to keep in mind around Julesburg, Ft. Morgan, Grand Junction, Montrose, and Durango.

Slow improvement continues for the Western Slope

500 millibar winds are transporting heavier smoke in the northwestern United States mostly to the north of Colorado. Image courtesy of the NOAA Storm Prediction Center

The upper level winds over the western United States continue to shift as an upper level high pressure system builds over the desert southwest. The result is less smoke moving into western Colorado from fires to the west and northwest. All air quality advisories west of the Continental Divide will be allowed to expire at 9am Saturday morning.

This does not mean that the air is squeaky clean. Light to moderate levels of smoke remain which could still cause some discomfort, including irritated eyes, nose, and throat. For those that suffer from heart or lung ailments, it is still probably a good idea to take it easy this weekend. The building heat across western Colorado will also be a concern with afternoon temperatures topping 100 degrees in many areas, including Grand Junction.

There will be some areas in western Colorado that will see some locally heavier smoke. This is true in areas near the Elk fire and the Gold Mountain fire. The worst of the smoke will be during the early morning hours along Highway 550 from Ridgway north to Montrose, Highway 149 north of Lake City, and Highway 50 near Blue Mesa Reservoir in Gunnison County.

Eastern Colorado is also seeing levels of mostly light smoke which is currently in the "Moderate" category. One area that could see an increase in smoke over the next 24 hours is northeastern Colorado. This includes the northern Front Range region of Denver, Boulder, and Ft. Collins. It also includes the adjacent plains to the east, where smoke levels could increase for areas to the east of Interstate 25 and to the north of Interstate 70. This area includes Greeley, Fort Morgan, Julesburg, Burlington, and Limon.

There is still some uncertainty to the timing and amount of smoke that might impact this large area, so no additional advisories are being issued at this time. We will be monitoring the situation throughout the weekend and will post here if a new advisory is issued. Please keep in mind that the northern Front Range region remains under an Action Day for Multiple Pollutants until at least 4pm Saturday as the combination of smoke and high ozone continues to cause health concerns along the I-25 urban corridor.

 

Smoke subsides for some in the state, effects continue elsewhere

Smoke is still in the picture on Friday, but the Air Quality Health Advisory area is smaller than yesterday. Some areas in Colorado will see improved air quality today, but smoke from fires in-state and to our north will impact northern Colorado, southwest Colorado, and the northern Front Range.

What's driving this change? A shift in the upper- level winds. Earlier this week, upper-level winds from the west brought smoke into Colorado from Utah and Nevada. Today, the upper-level winds have shifted, coming out of the northwest. So today, the smoke from the Pacific Northwest will hit northern Colorado, but many counties on the Western Slope are getting a break.

Air Quality Alerts remain in effect for some parts of Colorado, but the area has shrunk significantly since yesterday.

In northern Colorado, smoke from out-of-state fires is still lingering. A blanket of heavy smoke hangs over the northwest corner of the United States, including Oregon, Washington, Idaho, Montana, and Wyoming. Colorado is on the southeastern edge of this smoke, so northern counties in Colorado are seeing the impacts. 

Heavy smoke is impacting much of the northwest. Image from the AirNow Fire and Smoke Map.

In the Northern Front Range, smoke from out-of-state fires is sticking around. Moderate smoke and haze are possible in Fort Collins, Greeley, and the Denver Metro area today. High ozone is also expected on Friday afternoon, so take precautions if you are sensitive to smoke or ozone.

In southwestern Colorado, the Elk Fire, Gold Mountain Fire, and Rio Blanco Fire are producing smoke. Moderate to heavy smoke is possible on Friday and Saturday morning.  An Air Quality Health Advisory is in effect.

Finally, the 310 Fire is burning in Garfield County, near Parachute. We do not expect heavy smoke from this fire today, but we will update the blog if that changes.

If smoke is heavy in your area, take steps to limit your exposure and protect your health if possible.

Areas of smoke remaining on Thursday with a slight shift

Wildfire smoke will remain in the conversation for many areas of Colorado on Thursday and Friday. There is a bit of difference between the source of smoke for different areas, yet the outcome is much the same. Let's go through it all.

Western and southwestern Colorado will continue to receive smoke from fires in Utah and Nevada. The Elk and Rio Blanco fires in Colorado will also add smoke to the mix. All of these fires remain active, with hot, dry, and breezy weather, so smoke will remain a concern.

Northwestern and central Colorado, the Front Range, and portions of the eastern plains will receive smoke transported from the northwestern US. Many fires continue to burn in Wyoming, Montana, Idaho, and the Pacific Northwest, sending smoke toward Colorado. Smoke will follow upper level winds into our area, and will descend to the surface. The locations that will see the most surface smoke depends on influences from terrain and vertical mixing of the atmosphere. This pattern shifts each day, so the footprint of the advisory has changed on Thursday. El Paso and Pueblo Counties were removed from the Smoke Advisory, and Morgan County was added.

Map of fire incidents from InciWeb, the national fire incident information system. Map shows the multitude of fires that may affect Colorado air quality. Note: Not all incidents shown may be active.

This does not mean that other areas of Colorado will be smoke-free. We expect hazy skies and light to moderate levels of smoke to be present in all areas of the state.

We encourage everyone statewide to remain aware of the potential for quickly changing levels of smoke, especially in areas covered by advisories and alerts. Reduce heavy physical exertion if possible, and be prepared to take actions to reduce health impacts due to smoke.

We will end this post with a glimmer of hope, and a bit of caution. The large scale weather pattern is expected to shift, beginning on Friday. This will push smoke from upwind states further north, and may reduce impacts in some areas of Colorado. We hope that this change brings some relief from the impacts from smoke. Caution remains in this message because this shift in weather will bring increasing temperatures back to Colorado. Hot and dry weather may pose its own risks to fire behavior and public health.

Hang in there folks. We will keep updates coming so you can stay informed.

Potential for heavy smoke continues for western and central Colorado, with some improvement for the eastern plains

Air quality remains a concern across large parts of Colorado. It's a complex scenario so let's move from west to east across the state.

Western and central Colorado are seeing a wide variety of air quality conditions Wednesday morning. There is somewhat heavy smoke in parts of the San Juan Mountains in southwestern Colorado. This is especially true in some of the higher terrain to the west and southwest of Telluride and Silverton. Lower smoke levels can be found further north in Grand Junction, Aspen and Steamboat Springs. However, the Air Quality Health Advisory for Wildfire Smoke will be extended for the entire Western Slope until at least 9am Thursday. Why is this, if some areas are currently seeing lower levels of smoke? 

First, wildfires to the west and northwest of Colorado remain very active. The satellite image below from yesterday afternoon shows massive smoke plumes in Idaho and Utah moving from west to east.

GeoColor satellite image Tuesday afternoon of smoke plumes to the west of Colorado. Satellite image courtesy of Colorado State University's CIRA Slider

Some of the smoke from those plumes yesterday is likely over Colorado this morning. That smoke could mix down to the surface over central and western Colorado by this afternoon. Additionally, those fires are likely to be active again today and send more smoke in the direction of Colorado.

Second, red flag warnings are in effect today for large sections of central and western Colorado. If new wildfires start today, that will add even more smoke to the atmosphere. We also need to keep an eye on ongoing wildfires across the state. These include the Elk fire north of Lake City, the Rio Blanco fire south of Pagosa Springs, and the Indian Creek fire near Rabbit Ears Pass between Kremmling and Walden. The Elk and Indian Creek fires are especially concerning today as both lie within the red flag warning zone.

Further east, the Interstate 25 corridor is also seeing elevated levels of particle pollution Wednesday morning. This includes Ft. Collins southward through Denver and Colorado Springs to Pueblo. We are not expecting additional smoke in these areas today, but there is enough smoke currently along with normal urban pollution to keep all of these areas under an advisory today. Please keep in mind that along with particle pollution, high ozone will also likely be an issue today around the Denver metro area, Boulder, Longmont, Greeley, and Ft. Collins.

Webcam image looking west from Monument Hill/Kelly Air Park between Denver and Colorado Springs. Webcam image courtesy of Federal Aviation Administration WeatherCams

The one area removed from yesterday's advisory is the eastern plains. This includes most areas to the east of Interstate 25. Although we are not expecting see rapid improvement in air quality across the plains today, current smoke levels are in the moderate category and we are not anticipating any additional smoke through at least tomorrow morning.  The latest county advisory map of Colorado is below.

Map of current air quality advisories in Colorado

Colorado fires flaring up

The Elk fire to the north of Lake City in northern Hinsdale County has flared up on Tuesday with the increasingly hot and dry weather conditions. This entire area is already under an Air Quality Health Advisory for Wildfire Smoke due to smoke being transported from outside of Colorado (see this morning's blog post below for more information).  But the smoke from this fire will only make air quality worse in locations near the fire. 

Downwind smoke impacts could be felt to the east of the fire in northern parts of the San Luis Valley, including Saguache. Overnight, smoke could get heavy to the north of Lake City along Highway 149.

Meanwhile, the Rio Blanco fire to the south of Pagosa Springs in Archuleta County is also showing an increase in activity. This fire is a bit more isolated, so public health impacts will likely be more limited to areas in very close vicinity to the fire. One thing to keep in mind is that not only particle pollution is elevated in Archuleta County. Ozone is pretty high too, so an advisory for multiple pollutants has been issued for both Archuleta and La Plata counties, including the Southern Ute reservation.

Band 7 shortwave satellite image of the Elk and Rio Blanco fires in southwestern Colorado. CIRA slider image courtesy of Colorado State University

Smoke to affect all areas of Colorado on Tuesday and Wednesday

Wildfire smoke from several western states will affect air quality in Colorado on Tuesday and into Wednesday. An Air Quality Health Advisory for Wildfire Smoke has been issued for all counties in Colorado.

The reason that the advisory covers such a large area is that there are several ways that smoke is moving into our state. Fires in Utah and Nevada are producing large plumes that are moving east. This smoke is now in western areas of Colorado, and will move further south and east on Tuesday. These fires were very active on Monday. Large columns of smoke rising into the atmosphere are seen on the left side of the image below. 

Late in the day on Monday, a cold front pushed additional smoke into eastern and central Colorado. This is seen in the upper right areas of the image below.

Satellite image of smoke arriving in Colorado at 7 pm MDT on Monday August 3, 2026. Transport is from the west due to fires in Utah and Nevada, and from the northeast due to fires in several upwind states. Image courtesy CSU/CIRA/NOAA.

As all of this smoke moves through our region, we expect levels of fine particulates to create air quality impacts in all areas of Colorado. Concentrations will likely differ in time and place. However we want to stress that the potential for smoke will be present across all of Colorado on Tuesday and into Wednesday morning. Please remain aware of air quality conditions in your area, and take steps to reduce health impacts.

Air Quality Health Advisory has been expanded

 

An Aerosol Optical Depth image reveals heavy smoke (red shading) in the atmosphere over large sections of Colorado

Wildfire smoke from multiple fires across the western United States is having big air quality impacts in Colorado. The Air Quality Health Advisory that was issued Monday morning for several counties has been expanded. In addition to the communities we mentioned in the last blog post below, places like Rifle, Vail, Aspen, Breckenridge, Fairplay, Canon City, Colorado Springs, and Pueblo will also be impacted by periods of moderate to heavy smoke. Please take action to protect your health from wildfire smoke.

The northern Front Range region will not be spared. A cold front is pushing towards northeastern Colorado. That cold front will likely bring smoke with it from Wyoming and western Nebraska. Be prepared for smoke to increase again tonight in Greeley, Ft. Collins and southward into the Denver metro area. Along with increased particle pollution, the smoke could also enhance ozone across the northern Front Range during the afternoons and evenings.

Heavier smoke (orange and red dots) will move southward into Colorado Monday night with a cold front. Map courtesy of the EPA's Fire and Smoke Map

The upper level winds will likely continue to transport smoke in the direction of Colorado over the next few days, so please remain alert to rapidly changing air quality conditions in your area.

Starting the week with wildfire smoke across parts of northern Colorado

Wildfire smoke has made a return after a few weeks of relatively good air quality across northwestern Colorado. Elevated levels of fine particulate matter can be found Monday morning in Craig, Steamboat Springs, Walden and Granby. Some smoke has even spread as far east as northern parts of the Front Range region, including Ft. Collins and Boulder.  An Air Quality Health Advisory has been issued for all of these areas through 9am Tuesday morning.

Counties currently under an Air Quality Health Advisory for Wildfire Smoke, shaded dark grey. The map and advisory information can be found at the CDPHE air quality webpage

Several wildfires in Nevada and Utah are the origin of this smoke. However, an additional dose of wildfire smoke may arrive later this afternoon and evening from the north as many fires also remain active across the northwestern United States. With the upper level winds shifting over the next 24 hours, it is possible that Colorado could be contending with a prolonged stretch of wildfire smoke conditions this week. Please continue to follow the blog as the outlook could change rapidly over the next few days.