Navigating the Smoke Blog and Understanding the NowCast AQI

As Smoke Ready Week comes to a close, we’d like to review some important information for the upcoming wildfire season. Luckily, if you’re reading this, you know where to find the Washington Smoke Blog – the state’s one-stop-shop for wildfire smoke information. 

Smoke over Mt. Baker - Snoqualmie National Forest (USFS)

Navigating the Smoke Blog

At the top of the Smoke Blog, you’ll see a map with Air Quality Index (AQI) values from monitors and sensors across the region. The colors and numerical values indicated by each sensor/monitor reflect "nearly" current air quality conditions, called the NowCast AQI (See section below for more information about the NowCast AQI). By moving the slider in the top left corner of the map, you can view an air quality forecast for the next 5 days. Smoke conditions can change quickly, so remember to check the forecast for daily updates. 

Below the map, there are several tabs. These are pages with more information about specific topics, including air monitoring, health impacts, and regional wildfire contacts. There is also a tab with information about wildfire smoke, health risks, and the AQI in Spanish (“En Español”). 

Under these tabs is the main section of the blog. The newest post will be at the top. If you have a question or comment, you can put it in the comments section of a blog post. Click “Comments” at the bottom of a post to open the comments section. 

We monitor and respond to questions and comments during business hours: Monday – Friday, 8 am – 5 pm. 

To the right of the blog’s main section is a column with additional links, including burn ban information, National Weather Service advisories, and archived posts. 

Smoke resources

The Smoke Blog is an excellent place to find all the resources you might need during wildfire season. We know there's lots of information out there – especially when fires and smoke get bad. Everything posted here is backed by wildfire, smoke, and health experts across several public agencies. 

In addition to the Fire and Smoke map at the top of this page, check out the Washington Air Quality Map and EPA’s AirNow. These are all reliable sources of air quality data. 

For more information about health effects, visit the Department of Health’s Smoke from Fires page. DOH also has a helpful page about portable air cleaners. 

Below is a list of a few more key resources for wildfire and smoke season: 

• EPA’s Smoke Ready Toolbox

• Watch Duty – Wildfire Maps and Alerts

• How to make your own clean air fan (video)

NowCast AQI

Wildfire smoke can cause rapid air quality deterioration. Yet different air quality reporting sites publish data at different intervals. Agency air monitors report the hourly averaged data once an hour. When smoke rolls into an area, air quality maps will not receive the data until the following hour.

State and Federal air quality maps use these data to calculate a ‘NowCast’ value, which relates current and previous hourly PM2.5 concentrations to the Air Quality Index, resulting in the color scale you see on the map. The Fire and Smoke map (shown above), Washington State Department of Ecology (AirQualityWA - SiteMap), and AirNow (airnow.gov) report the NowCast value.

Adverse health effects depend not only on the amount of smoke in the air, but the length of time a person is exposed. The NowCast value incorporates both these factors to provide a more accurate risk assessment. Visit NowCastFactSheet2D_EPA.pub for more information on NowCast AQI and how it is calculated.

In contrast, the Purple Air real-time map (https://map.purpleair.com/air-quality-standards-us-epa-aqi) provides near instantaneous air quality depending on the averaging period chosen by the user. The Purple Air data on this map are not subject to quality control and validation and therefore may not be accurate, however the Purple Air sensors, in aggregate, provide a decent snapshot of instantaneous air quality conditions.

Stay safe this summer!

Thanks for tuning in during Smoke Ready Week! Be sure to bookmark the blog and share with others for regular updates over the next few months.

Light Smoke in Eastern Washington

If you are smelling wildfire smoke in Eastern Washington Thursday morning, you are not imagining it. Light smoke concentrations are impacting the area from the Tri-Cities up north through the Okanogan Valley and east to Spokane. Most monitors are reading in the MODERATE category, with some sensors suggesting UNHEALTHY FOR SENSITIVE GROUPS around Lake Roosevelt and southern portions of the Colville Reservation. 

EPA Fire & Smoke Map as of 10:27 a.m., June 12, 2025.

A few wind-driven wildfires took off yesterday afternoon across the eastern Columbia Gorge and lower Columbia Basin. The largest of the two are the Rowena Fire near the Dalles and the Hatch Grade Fire south of Wallula, both around 2,500 acres. Crews are getting those fires under control quickly with the help of aggressive aviation tactics. 

The Rowena Fire burning near The Dalles, Oregon, on June 11, 2025. Via the Wasco County Sheriff's Office.

Smoke from these fires followed the winds to the east and northeast and has settled across eastern Washington this morning. Smoke concentrations should gradually diminish as mixing heights rise and winds increase this afternoon.

Hourly averaged PM2.5 concentration around Airway Heights, WA just west of Spokane. After rising sharply overnight, smoke concentrations are falling rapidly late this morning.

Additional smoke is possible over the next few days, but critical fire weather conditions will be easing on Friday as cooler temperatures are expected across the state. That will likely help crews further control existing fires and reduce smoke impacts accordingly. Unless new fires pop up, this morning's smoke impacts will probably be the maximum experienced through the weekend. We will continue to monitor and provide updates as needed. 

If you weren't already motivated to get yourself ready for wildfire smoke, then perhaps you are now! Stay tuned for one more blog post on Friday to wrap up #SmokeReadyWeek.   

Smoke Ready: When does smoke usually arrive in Washington?

We're in the middle of Smoke Ready week, and perhaps you might have wondered, "Why is Smoke Ready Week in mid-June?" As it turns out, there's a good reason for it. Today, we'll discuss when smoke has impacted Washington in recent years and the weather patterns that made it possible

Pictured below are tile charts from the EPA showing the maximum AQI values in two areas of the state, Seattle-Tacoma-Bellevue and Spokane-Spokane Valley. Each tile represents a day of the year with the years increasing from top to bottom. Months are labeled from left to right at the top.

During the winter months, it's not uncommon to see Moderate (yellow) air quality due to residential, industrial, and transportation pollution. You might also notice a spike from fireworks around Independence Day. But typically, air quality from April through June ranges from Good (green) to Moderate.

Since 2010, the earliest Unhealthy (red) air quality day due to wildfire smoke in either area was in 2014. Air quality around Spokane and much of northeast Washington deteriorated on July 19th during the early stages of what would become the Carlton Complex Fire near the Methow Valley. 

In 2020, air quality remained mostly Good throughout the summer on both sides of the state until September when a prolonged period of Very Unhealthy (purple) to Hazardous (maroon) conditions impacted the entire state. 

Perhaps the biggest outlier is 2022 when an exceptional smoke event impacted the state well into October. Perhaps the most surprising part of this event was the disparity between western and eastern Washington. The Seattle area saw a prolonged period of Unhealthy to, at times, Hazardous air quality. In comparison, eastern Washington saw only a few days of Unhealthy air. This was due to several large fires burning in the Cascades combined with a strong east wind event.

With these Unhealthy air quality events in mind, we can look to the past to see what weather patterns make smoky days more likely. First, let's look at Spokane's case using the dates of Unhealthy (or worse) wildfire smoke events. We'll omit the elevated AQI values around the Fourth of July for each of the following examples. Pictured below is how the upper-level weather pattern on those days compares to the 30-year average from 1991 to 2020. 

Notice the orange and red sitting right over Washington. This indicates above normal conditions, or an upper-level ridge of high pressure. Now, let's venture down to the ground look at Sea Level Pressure.

You can see orange and red in Montana and Wyoming indicating high pressure and blue offshore indicating low pressure. Since air flows from high to low, this would indicate Spokane tends to get smoky when a ridge is overhead and winds at the surface are out of the east-northeast. 

Analyzing Unhealthy air quality days in the Seattle area reveals a similar pattern, but there are some key differences.

On average, the upper-level ridge on Unhealthy air quality days for the Seattle area is centered just north of the state. Overall, not so different from Spokane.

The surface weather pattern, however, is more revealing. Notice for Seattle's case, the darker shade of blue hugs the coastline while, for Spokane, it's further offshore. As such, the change in pressure across the Cascades is greater. This suggests that, for widespread smoke to occur in Western Washington, a moderate to strong offshore wind event is almost always needed. This pattern in the summer typically results gusty east winds and lower relative humidity along the west slopes of the Cascades. You might hear your local meteorologist talking about a "thermal trough" during these events.

In summary, smoke season typically starts earlier east of the Cascades. The source of the smoke can vary, but most often impacts the surface when high pressure is overhead and surface winds are out of the east. In western Washington, smoke is more likely once the calendar flips to August and typically requires a stronger offshore wind and active wildfires in the Cascades.

This is why Smoke Ready Week is held in June! Typically, this gives us at least a month to gather supplies and make a plan. That way, when "thermal trough" and "upper-level ridge" enter the forecast and fire is on the landscape, you're already Smoke Ready!

It’s time to get Smoke Ready!

Now is the time to get #SmokeReady! Things are heating up in the PNW, and with the excitement of warm weather comes the threat of wildfires. Cities across the Midwest and Northeast are already suffering the effects of wildfire smoke from Canada, reminding us to prepare for a season of smoky air here in Washington.

Preparing early means less stress when the smoke hits. So, how can you make sure you’re #SmokeReady?

S – Stay Informed
M – Minimize Exposure
O – Optimize Your Air
K – Keep a Plan
E – Ease Your Mind

We’ll be posting throughout the week on #SmokeReady topics. Today, we’ll focus on smoke impacts on health and how to prepare for when smoke arrives.

Smoke and your health

Inhaling wildfire smoke is harmful to our health. Anyone who breathes in smoke may experience symptoms, though children, adults over 65, pregnant people, and people with lung or heart conditions are at higher risk. Everyone reacts to smoke differently, and smoke impacts can occur at any level of smoke. Symptoms can include:

• Irritation of eye, nose, and throat
• Coughing, sore throat, headaches
• Wheezing and shortness of breath
• Worsening of existing conditions, with symptoms like asthma attacks, chest pain, or irregular heartbeat. 

How to prepare for wildfire smoke

The best time to prepare for wildfire smoke is before it’s in the forecast. Here are some steps you can take to plan ahead:

• For people with lung and heart conditions, talk with your medical provider to make a plan.
• Plan how you will clean your indoor air.
• Consider what supplies you might need, such as N95 masks, portable air cleaners, and HVAC filters. These items are often in short supply after smoke arrives.

When there is wildfire smoke, take the following steps to protect yourself and your family:

• Stay inside with cleaner indoor air: 
• Close windows and doors unless it’s too hot to maintain safe temperatures.
• Avoid activities that add to indoor air pollution, such as smoking or burning candles.
• Filter indoor air with a portable air cleaner with a HEPA filter, a box fan filter, or your HVAC system set to recirculate.
• If you are not able to maintain cleaner air at home, go elsewhere for cleaner air.
• Pay attention to symptoms and seek medical help if needed.
• If you must go outside, wear a well-fitting N95mask, limit physical exertion, and stay hydrated. 
• Local health departments and fire districts are great resources for finding wildfire and cleaner air shelters.

Wildfires and smoke events aren’t just dangerous, they’re also stressful and frightening – especially to those without a close support network. Check in on your neighbors and people in your community before and during a smoke event.

Creating a support network in your community will help everyone manage the stress, anxiety, and health risks of wildfire season. Make sure to take care of your own mental health by seeking out activities that keep you calm and grounded.

For more information on how to protect yourself, visit DOH’s Smoke from Fires page.

Welcome to Fire Season 2025

Welcome to the Washington Smoke Blog and to wildfire season 2025! This post will cover the ongoing Canadian fires, a seasonal outlook, and a preview of "smoke-ready week" next week (June 9-13). 

Canadian Smoke

Fires (shown as orange dots/thermal anomalies), clouds, and smoke across Canada and the Northern U.S. on June 6, 2025. Data from NASA Worldview.

Canada is off to a fast and furious start to their fire season, particularly in the central provinces of Alberta, Manitoba, and Saskatchewan. Activity in far northern British Columbia is also picking up. Smoke from these Canadian fires has been drifting into portions of the central and eastern U.S. at times over the last few weeks, deteriorating air quality and making news headlines. While the size and severity of these fires is above normal, the timing is typical for that region. In most years, some fires typically establish across the boreal forests of central and eastern Canada in late Spring and early Summer (May-June). This is the period after snow melts but before the vegetation ‘greens up’ in the early summer months. Smoke from Canadian fires thus far has remained east of Washington state and our air quality remains good. This is typical - Washington generally does not experience ground-level smoke impacts from fires that occur east of the Rocky Mountains. 

We CAN experience smoke from Canada when fires establish closer to home in the mountains across southern British Columbia, but the timing of that would be more in line with our typical peak of fire season (July to September). Activity in that area is minimal right now but we’ll be monitoring closely for new activity as we head deeper into summer.

A Dry Spring

A key trend in Washington heading into fire season is our lack of late spring precipitation. This has been true across most of the state but is particularly notable across the dry forest environments along the eastern slopes of the Cascades and Blue Mountains. On average these are some of our most active regions for wildfire and this year they are heading into fire season having gone without significant rainfall for months.

Precipitation anomaly (% of normal) over the last 60 days - from April 6 to June 4, 2025. Much of the Pacific Northwest has seen precipitation amounts only 25-75% of the 1991-2020 normal. Data via climatetoolbox.org.

Here is another way to look at recent precipitation trends, using percentiles. Areas in dark brown have seen their lowest precipitation amounts in the April 6 to June 4 period since the dataset began in 1979! Data via climatetoolbox.org.

In spring and early summer, vegetation typically goes through a period of growth and then subsequent curing and drying. Without much recent precipitation, the curing and drying process is already well underway across the lower-middle elevations of central and eastern Washington. Grasses and shrubs are ready to burn in many areas. In fact, recent weeks have already featured a handful of early season fires in lower elevations of eastern Washington and Oregon. As heat builds further into the weekend, conditions are rapidly becoming favorable for additional fire activity in those areas – especially when combined with incoming strong winds Monday through Wednesday next week. 

Probability of the hot-dry-windy index exceeding the 95th percentile, valid next Tuesday, June 10. Data via https://hdwindex.fs2c.usda.gov/index.html.

Cooler temperatures and lighter winds should arrive by the end of next week to ease concerns for significant fire growth. Additionally, even with the lower than normal precipitation trends, the higher elevations and much of western Washington are still limited in their fire growth potential by live, green vegetation. That will change as we head later into the summer and things dry out further.

Forecast Summer Conditions & Lightning Ignition Potential

After the initial period of potentially critical fire weather early next week across central and eastern Washington, what will the rest of summer look like?

The NOAA Climate Prediction Center has much of the U.S. West favored for above normal temperatures this summer, including the Pacific Northwest. Hot temperatures combined with low relative humidity can rapidly pull moisture out of vegetation, increasing the potential for that vegetation to burn. There are certainly other factors - wind, vegetation type, short-term weather patterns, topography, and fire suppression capability, to name a few. And of course, we still need ignitions to have fire. But unusually warm summer temperatures will generally stack the odds in favor of larger and more difficult to manage fires. For example, July 2024 was extremely hot across the region and played a major role in readying the vegetation across Oregon for what ended up being a record fire season in their state.

We can also look at the seasonal precipitation outlook which is suggesting below average rainfall across the Pacific Northwest for the rest of the summer. Keep in mind that summers are typically dry in our region to begin with, so the precipitation outlook is a minor factor relative to the temperature outlook. 

One of the main uncertainties for this season is how the southwest monsoon will evolve. On occasion, moisture from the southwest monsoon can work its way northwards, creating enough moisture and instability in the upper part of the atmosphere to trigger thunderstorms - but not enough actual rainfall reaching the ground to provide benefit. These dry lightning episodes can ignite many new fires all at once across the landscape, often in difficult places for firefighters to access. At this point we don’t have good insight into the potential for dry lightning over the summer. But it’s something we are watching closely and could rapidly change the outcome of the season, especially given the background warmth and dryness that's expected.  

Putting it Together: Significant Wildland Fire Potential

With the dry spring and likely warm summer, the odds favor above normal fire activity across the entirety of the Pacific Northwest. This is reflected in the official forecasts produced by the National Interagency Fire Center. These forecasts paint the picture for above normal large fire activity starting in June across eastern Washington and Oregon before expanding across the rest of the Pacific Northwest in July and August – potentially even continuing through September.

Many Smoke Unknowns - And The Importance of Readiness

Though a very active fire season is likely, it's never a guarantee. Additionally, even if we have large fires on the landscape there is an entire other set of questions we need to analyze about smoke:

• Are fires becoming established in forests or lighter fuels such as grass and shrubland? It's the forest fires that create much more smoke and for longer periods of time.
• How far away are fires around the region to Washington communities?
• Where is the wind blowing the smoke? Towards or away from where people live?
• Is the smoke located at ground level, where people breathe, or simply moving overhead higher up in the atmosphere?

The smoke blog exists in part to help you answer these questions throughout the season and stay up to date on the latest information. 

While the local air quality is still good, now is a great time to prepare yourself for smoke! In fact, next week (June 9-13) is officially "smoke-ready week", and we’ll be kicking it off with additional blog posts starting on Monday! Stay tuned ...