2025 wildfire season: air quality in review

Monitoring sites in the Wenatchee area are still observing lingering impacts from the Labor Mountain Fire, but with recent rain and cooler weather, wildfire season is winding down. It's a good time to look back at this year's wildfire season from an air quality perspective.

Statewide Overview

In terms of the number of smoke-impacted days, this season began quietly. Up until mid-August, there were very few days with elevated PM2.5 concentrations, based on data from 133 air quality monitors tracking PM2.5 across the state (note that monitoring sites do not cover every location in the state and some areas experienced worse smoke than what is captured by the statewide monitoring network). Early season smoke impacts were localized, primarily from the Bear Gulch Fire near Lake Cushman and the Pomas Fire northwest of Entiat.

Conditions changed quickly at the end of August, when a combination of lightning-sparked wildfires, hot and dry weather, and light winds led to an increase in unhealthy air quality days across Central and Eastern Washington. Overall, the 2025 season ended up resembling 2021 and 2022 more than the relatively smoke-free 2024.

Total number of USG or worse air quality days observed by air quality monitors over the last decade.

While no region was entirely free from smoke, Central Washington experienced the most sustained impacts this season. The Wildcat, Lower Sugarloaf, and Labor Mountain Fires were the primary contributors. Although the Pomas Fire started early in the season, it had minimal impacts on air quality compared with the larger, more smoke-producing fires. Northeast WA also experienced prolonged smoke impacts from numerous regional fires in September. Southeast WA dodged most of the heaviest smoke but still experienced occasional impacts from smoke drifting into the region. Western WA (more below!) experienced intermittent periods of smoke from regional fires when shifting winds carried smoke towards the Puget Sound and NW WA.

Total number of USG or worse air quality days observed by air quality monitors this summer, sorted by region.

To better illustrate the timing of smoke impacts this summer, the plot below shows daily air quality levels for each county in the Washington with an air quality monitor. Each row represents the daily average from the most impacted monitor in that county, with counties organized by geographic region. Aside from localized impacts at Lake Cushman, most of the state experienced good and moderate air quality for most of the summer until fire activity drastically ramped up at the end of August and into September.

Daily air quality index levels for each county in WA this summer. Temporary monitoring at Lake Cushman is also included.

The Bear Gulch Fire

The 2025 perimeter of the Bear Gulch Fire (pink) compared to previous fires in 2006 (blue) and 1979 (green). 

The Bear Gulch Fire near Lake Cushman created an unusual smoke season for western Washington. The fire, started by human activity on July 6, frequently caused poor air quality in communities along the Hood Canal and in Mason County throughout July, August, and September. Between September 14th and September 20th, the fire nearly doubled in size growing from 10,851 acres to 19,092 acres. This rapid growth caused several hours of unhealthy air in Port Angeles on September 16th & 17th and in Mason and Thurston Counties September 19th & 20th.  At just over 20,000 acres, the Bear Gulch Fire holds the record as the largest wildfire in the Olympic National Park (ONP) since its establishment in 1938, breaking the previous record of 1,175 acres. Between 1985 and 2024, roughly 900 recorded wildfires burned a total of 4,300 acres in the ONP. Major fires in the Olympics typically burn between 10 and 500 acres. While they often smolder for several weeks, rarely do they generate significant smoke impacts beyond the immediate vicinity. The Bear Gulch Fire produced multiple pyrocumulus clouds, hazy skies, and even a visible smoke plume that stretched across the state on August 13th. The first wetting rains fell over Bear Gulch in early October and continuing showers have dramatically slowed fire growth and smoke production. All evacuation orders have been lifted, and the US Forest Service has transferred fire management to local units. 

Bear Gulch burn scar from satellite imagery on October 13.