Fall Has Arrived - Is Fire Season Over?

It's late September and we've now passed the Fall equinox. With the longer, cooler nights and occasional precipitation chances, fire season is on its way out. But we're not completely out of the woods yet. 

Strong Winds Today

A strong cold front is crossing the state from west to east today.

Frontal system approaching the Pacific Northwest Wednesday morning. Image via Colorado State University (CIRA/RAMMB).

In western Washington, this will bring periods of steady moderate-heavy rain -- especially in the Olympics and North Cascades. Good for knocking out any residual fire danger in those areas!

Total precipitation forecast (inches) through Friday morning. Via WeatherBell.

In eastern Washington, however, showers will be hit or miss. Most areas will not receive a wetting rain. Instead, strong winds are expected with potential for gusts near 40-45 mph this afternoon. 

The wind combined with low relative humidity and warm temperatures east of the Cascades is spiking the 'Hot-Dry-Windy' index well above the 95th percentile for this time of year. 

 Image via https://hdwindex.fs2c.usda.gov/probs.html.

With that in mind, we'll need to keep an eye out for any new fires in some of the grass and sagebrush across the Basin. There is potential for rapid fire spread if anything sparks up. Additionally, areas of blowing dust and reduced visibility are possible with the strong winds. 

Looking Ahead

Forest fire season will be coming to an end rapidly, especially on the west side of the state where significant precipitation is received. In eastern Washington, winds calm down after today, but dry weather continues through the weekend with additional strong winds possible next week. We generally won't be able to rule out additional fires in the grass/sagebrush through October, depending on weather and ignitions (or lack of ignitions). On the bright side, grass fires are typically put out quicker and have less smoke impacts than forest fires. We'll continue to monitor closely until fire season is completely over! 

2024 wildfire season: air quality in review

Although a few fires continue to burn in the state, smoke levels remain low, and the forecasted weather is not conducive to wildfire growth. Let's take a look at how this wildfire season's air quality compares to previous years.

In terms of the number of smoke-impacted days, this summer looked more like the relatively smoke-free summers of 2016 and 2019 rather than more recent years. The summer wasn't smoke-free, but we avoided significant, widespread, and prolonged smoke impacts. One way to put this year in perspective is to review the total number of smoky days at air quality monitoring sites in Washington since 2012, broken up into region and only including days when the air quality reached Unhealthy for Sensitive Groups or worse:

For all regions, the number of smoky days this summer was much less than previous years. There were only 7 days of Unhealthy air quality in the state this summer--that's from 115 air quality monitors and sensors that continuously measure PM2.5. To put that number into context, the 2020-2023 seasons averaged 206 days of Unhealthy or worse air quality. Looking a little further, there were only 413 hours (about 12% of the total monitoring hours) of Unhealthy or worse air quality this summer. That's an order of magnitude less than the number of Unhealthy or worse hours in 2023 (3,129 hours). About 20% of those 413 hours were associated with 4th of July fireworks.

We can also put this season into context by estimating approximately how many Washingtonians were exposed to extended periods of poor air quality in comparison with recent smoke events. While communities near wildfires experienced smoke this summer, far fewer Washingtonians were exposed to unhealthy air compared to the past few years.

This wildfire season Washington largely escaped significant smoke impacts from neighboring states and Canada. While there were a few large wildfires in Central and Eastern WA (i.e., the Pioneer, Williams Mine, Swawilla, Retreat, Cougar Creek Fires), nearby communities were the most impacted. Favorable meteorological conditions were also on our side, including early season precipitation and a lack of significant easterly wind events. Quick actions by firefighters also helped to minimize smoke production from active fires. Thanks to everyone that recreated safely during critical fire weather conditions.

Weekly Smoke Recap and Forecast Outlook

Weekly Recap

Air quality is much improved now that we've made it to Friday. Smoke began to clear on Sunday as westerly winds started pushing the smoke out of western Washington.

Air quality remained Moderate to Unhealthy for Sensitive Groups for portions of central and eastern Washington on Monday, but started to turn Good by the end of the day.

After seeing some of the worst air quality in the state over the weekend, conditions did improve in southeast Washington. Due to proximity to fires in Idaho and eastern Oregon, however, Clarkston once again saw air quality regress to Unhealthy for Sensitive Groups on Wednesday. 

Fortunately, an incoming storm system would bring statewide relief from the smoke. Precipitation started at the coast late Tuesday and continued to spread east through Wednesday. By Thursday morning, several areas of the state saw a wetting rain. The biggest winners were at the coast, southwest Washington, and southeast Washington where totals over one inch were observed.

Even for those that saw little or no rain at all are finishing the week with Good air quality and much cooler temperatures than this time last week. Higher relative humidity is also keeping fire activity low in Washington, Oregon, and Idaho.

Smoke Outlook

Air quality will remain Good for the foreseeable future with Moderate air quality only near local sources of pollution. Wildfire smoke is not expected to be an issue in the short term with onshore flow and scattered showers continuing through Sunday morning.

Sunday afternoon, low level flow turns northerly and will persist through Monday. Dry conditions and temperatures near seasonal averages are expected.

A low pressure system tracking through southern Idaho may bring wraparound moisture to portions of eastern Washington early Tuesday. By Tuesday afternoon, a new system will develop off the coast bringing scattered showers mainly to western Washington.

East of the Cascades, breezy to gusty winds (25-40 MPH) are expected Tuesday afternoon. This will be the primary concern for elevated fire weather conditions next week along the east slopes and across the Columbia Basin.

Dry and warmer weather is likely to return sometime late next week or next weekend, but extreme heat seems unlikely for now.

Protecting crop workers under the sun and smoke

In the Pacific Northwest, cherries, peaches, plums and many other fruits mean summer — thanks to the people who harvest them. As climate change makes our region’s summers increasingly hot and smoky, researchers and policymakers are becoming more concerned about the health impacts on these agricultural workers.

“Agriculture workers, especially crop and tree fruit workers, often must work outside regardless of temperature or air quality,” said John Flunker, a postdoctoral researcher in the UW Department of Environmental & Occupational Health Sciences (DEOHS). “Harvesting duties frequently coincide with extreme heat or wildfire smoke. So, they're really on the frontlines of exposure.” 

In the past two years, the Washington State Department of Labor & Industries (L&I) implemented new permanent rules designed to protect outdoor workers from health impacts related to heat and wildfire smoke. 

In August, a team led by Flunker and Dr. Coralynn Sack, an assistant professor in DEOHS and the UW Department of Medicine, headed out to several apple farms in Washington’s Yakima Valley to get a clearer picture of how these stressors affect crop workers’ health and how the new rules are being implemented in the field. 

Read the full story

Air quality improvement after a hazy weekend

After a weekend of hazy skies, air quality throughout the state is improving as onshore flow pushes the smoke away. Most of the region observed moderate air quality over the weekend, with a few locations experiencing a few hours of USG and Unhealthy air quality. 

Higher elevations observed smoke as it was transported aloft from Oregon and began mixing down to the surface--the air quality sensor at the Mt. Rainier Visitor Center observed increased PM2.5 concentrations starting last Thursday. 

Monitoring sites in Vancouver recorded elevated PM2.5 concentrations on Thursday and Friday before conditions improved on Sunday.

Smoke from fires in Central Idaho impacted Southeast Washington over the weekend, and air quality is currently unhealthy in Clarkston. Smoke should decrease throughout the day today.

Outlook: Smoke will continue to move out of the region today. However, dry and windy conditions through this evening can lead to rapid fire spread. Please continue to be cautious with any potential fire sources. There are a couple fires to note--the ~100 acre Swauk Creek Fire 13 miles NE of Cle Elum began late yesterday afternoon and the Huckleberry Ridge Fire south of Pe Ell is now estimated at 293 acres. While there may be occasional localized smoke impacts, we don't expect substantial smoke production from these fires.

This week brings cooler temperatures and the potential for light precipitation across the state. Barring any additional fire starts, air quality should continue to improve. Enjoy the cooler temperatures and improved air quality!

Friday Smoke Snapshot and Updated Weekend Outlook

Friday Smoke Snapshot 

As expected, smoke is currently blanketing much of the state mostly due to wildfires in Oregon producing large plumes that have drifted north. In Washington, the Williams Mine Fire has also been more active in the past few days which has contributed to local smoke impacts. The Huckleberry Ridge Fire, burning in southwest Lewis County, began on September 4th. So far, it has burned 100 acres and is also contributing to localized smoke impacts. Additionally, the Whiskey Creek Fire on the Oregon side of the Columbia River in the gorge has seen increased activity with a smoke plume visible Friday afternoon.

Wildfire smoke over Washington as seen from the GOES-West satellite Friday afternoon.

Air Quality Advisories remain in place for the following counties: Clark, Cowlitz, Lewis, Skamania, and Wahkiakum, until Saturday morning. 
To learn more or find out if there’s an Air Quality Advisory in place for your location, check with your local clean air agency. Air Quality Advisories may be put in place, removed, or extended at any time.  
For Air Quality Advisories on Reservations in Washington, visit: https://www.epa.gov/farr/burn-bans-indian-reservations-id-or-and-wa

A closer look at some of the monitors in the state: 
 
As smoke moved north and west from Idaho and Oregon, Seattle saw a shift from Good to Moderate conditions Thursday continuing through Friday.    

 

Vancouver was closer to the sources of smoke and saw higher impacts with levels reaching Unhealthy at its peak before slowly improving back to Moderate levels late Friday morning.

As smoke made its way north and settled in at lower elevations, Enumclaw and other locations within the Cascade foothills saw levels reaching Unhealthy for Sensitive Groups.

Weekend Outlook 

With hot and dry weather remaining in place, active fire behavior is expected the next few days. Except at the immediate coast, winds in the low levels will remain out of the east-southeast with south-southeast flow aloft. This will continue to transport smoke aloft into Washington through Sunday morning.

For Saturday in western Washington, air quality concerns continue with scattered pockets of Unhealthy for Sensitive Groups expected. Areas of greatest concern will be the western Columbia Gorge into the Vancouver metro area as well as the foothills of the central and southern Washington Cascades. Depending on smoke output from the region’s large fires, isolated instances of Unhealthy air quality are possible. East of the Cascades, air quality is expected to range from Good to Moderate. 

Eventually, westerly winds will push cleaner air onshore. This will be a gradual process, and widespread Moderate air quality will likely persist into Sunday night or early Monday for western Washington. Smoke impacts may worsen east of the Cascades Sunday through Monday morning with some locations seeing AQI rise into the Unhealthy for Sensitive Groups range, mainly across southern Washington. Northern Washington should remain Good to Moderate. Eventually, air quality is expected to improve statewide Monday afternoon into Tuesday.

We are still expecting isolated thunderstorms to develop over the Cascades this weekend. Any new lightning-induced starts may bring new local air quality issues. 

Smoke Update and Outlook

Smoke Situation  

While things have been relatively quiet on fires in Washington, recent warmer and drier weather has increased fire activity and smoke production around fires in Oregon and Idaho. 

Localized smoke from fires in Oregon and Idaho. Courtesy: College of DuPage

 

Light, offshore winds are expected through Saturday which may bring light/moderate amounts of smoke over southern and western Washington. Air quality is expected to be Moderate for much of western Washington with some portions of southwest Washington seeing periods of Unhealthy for Sensitive Groups. New fire starts or an increase in smoke output from existing fires could lead to locally worse air quality. Smoke is expected to clear gradually this weekend. 

Air Quality Advisories are currently in place for the following counties: Clark, Cowlitz, Lewis, Skamania, and Wahkiakum. 

To learn more or find out if there’s an Air Quality Advisory in place for your location, check with your local clean air agency. Air Quality Advisories may be put in place or removed at any time.  

For Air Quality Advisories on Reservations in Washington, visit: https://www.epa.gov/farr/burn-bans-indian-reservations-id-or-and-wa 

 

Forecast Outlook 

Relief from the heat and the smoke will come in phases from west to east. The first phase begins Friday as the seasonably strong ridge overhead begins to weaken. This will allow cooler onshore flow to reach the immediate coast, but these effects will be slow to move inland.  

East-southeast winds will continue to transport smoke from fires in Oregon into Washington through early Saturday, but an approaching upper-level disturbance will continue to chip away at the ridge, further weakening it and pushing it to the east. This will allow temperatures west of the Cascades to begin to cool, and smoke impacts will begin to lessen. 

 

Fire weather outlook from the Storm Prediction Center highlighting the potential for dry thunderstorms in the Cascades on Saturday

This system does come with concern for fire danger. Isolated thunderstorms will be possible Saturday afternoon through early Sunday in the Cascades. Although the smoke situation will be improving with increasing onshore flow, fuels will be very receptive to new lightning ignitions.  

Onshore flow will bring cooler but still above average temperatures to western Washington on Sunday. Central and eastern Washington will remain warm with air quality concerns lingering. A stronger belt of westerly winds will impact the state on Monday as a system passes to our north. This will further alleviate widespread wildfire smoke, but at the same time will elevate fire weather conditions east of the Cascades.