September 10, 2020

Major Air Quality Threat For Puget Sound Sound and Western Washington

There is the potential for a major degradation of air quality over Puget Sound, a threat serious enough that vulnerable folks should be prepared.

Specifically, it is looking increasingly likely that some of the dense smoke produced by the fires in western Oregon will move northward and northeastward into western Washington, producing a serious degradation of air quality.

Potentially as bad or worse than we experienced in 2017 and 2018. 

The visible satellite image for today (top, 10:31 AM) and yesterday afternoon (bottom, 5:01 PM) shows the story.  There is a dense plume of wildfire smoke over northwest Oregon from the massive fires, and that plume of smoke is slowly moving northward.

Here in Puget Sound, we have been "protected" by the easterly (from the east) flow crossing the mountains, leaving us with the modest smoke remnants from eastern Washington.

But this is going to change in a major way as the weather pattern shifts and southerly flow develops over western Oregon and Washington.   Such southerly flow will bring smoke northward into western Washington. 

Let me illustrate our problem by the forecast winds at 2000 ft.   This plots show wind speed (color coded in knots) and wind speed/direction barbs (if you want a tutorial on how to read them, go here). 

Here are the winds at 8 AM this morning:  mostly from the east and thus protective of western Washington.

But tomorrow, everything changes with the winds switching so that they are from the south and southwest.  Very bad.  Would Oregon move smoke into Puget Sound.

And there is another major surge of southerly flow on Sunday. 

We can view the implications of the wind shift by looking at the forecasts of the wonderful NOAA/NWS HRRR smoke modeling system.  I will start by showing you predictions of near-surface smoke (purple is the worst, followed by red and orange).

At 5 PM today, only modest smoke over Puget Sound, but terrible over western Oregon.  A spur of smoke is moving into southwest Washington.

 But by 8 AM Friday morning, substantial smoke has moved into western Washington, and very dense smoke has extended over Portland.

Sunday is a day when things may potentially get even worse for Puget Sound. An east-west vertical cross section of the smoke at 5 AM Sunday shows the worst smoke moving northward over Puget Sound (the low area between the Olympics and Cascades in the cross section).    If that mixes down, the conditions will get very unpleasant.

 The bottom line is that Portland and Puget Sound residents should be ready for unhealthy to hazardous air quality conditions.  My colleagues in the Washington State Department of Ecology have just put out a smoke alert on their excellent web site (  And I just got an email from  Eric Saganic of the Puget Sound Clean Air Agency and they are working on messaging of this potential serious event as well.

To protect yourself, there are many things you can do.  If your home or apartment has forced air with a decent air filter, stay inside with the system running.  Fortunately, temperatures will cool into the  70s over the weekend.  Buy a good air filter and tape it to a box fan...that really helps.  Purchase a commercial air filter system (some are as low as $ 50-100).   If you can get an N95 mask, use it (but they are difficult to secure because of COVID).  Most COVID-19 masks (e.g., cotton masks) are not effective for wood smoke particles.  Don't exercise during bad smoke periods.  Finally, you can check the current air quality by going here.

My podcast tomorrow will delve in depth on the smoke situation.


KNKX surrenders to cancel culture. More information here.

If you want to support this blog and my podcast you can do it through Patreon:


  1. Cliff, thank you for all you do for us. Glad that you are still sharing your expertise and I will continue to support you.
    Capn GMT

  2. I had suspected that many of these fires had been started deliberately, now we have proof -

    Many of the fires here in Oregon occurred simultaneously, both in the valley and also on the coasts. I highly suspect these are also not coincidences. Try blaming those on Global Warming, Inslee.

    1. Global warming doesn't really start fires (exception being lightning), it just makes them extremely easy to spread.

      One could say that global warming is the responsible for the massive spread of these fires, but maybe not the start of the actual fires (again, aside from lightning which is a common fire starter).

    2. Foolish humans starting local fires, yup. Totally dumb and despicable. Just like so many of human activities since post industrial revolution (and now) have leading to well documented global climate change & warming, which are increasing the probabilities of extreme wildfires and other events. As Cliff shows in many of his weather blog posts,there are multiple causes of things like wildfires. Or, like saying a wood stove fire is ONLY caused by the lit match, when there'd be NO fire if someone hadn't laid it properly before the match was struck.

    3. "Global Warming" doesn't start any of these fires... It just creates the conditions where they can spread like, well, wildfire.


    5. Dear unknown - the local officials are just parroting what they've been told by their chain of commands. These are the same folks who've insisted that the past 100 days of rioting in downtown Portland were "mostly peaceful." Much of the downtown is boarded up and singed by flames via those same "protestors." Pay attention, and in the future stay in your lane.

    6. Thank you all for adding the refutation, emergency services are already dealing with enough without also dispelling pointless lies

  3. What kind of AQI are we talking about? Those graphics make it seem like we could be above 500 AQI this weekend.

  4. Is there a publicly available link to the NOAA/NWS HRRR smoke modeling forecast, so we can see updates in the future?

  5. Dr. Mass
    PLEASE tell me that this is not bound to become an annual phenomenon. You see, I d come to love the PNW for its landscape, but if this is the future, I’d rather find a job in the Midwest or something rather than tell my children tales of how beautiful summers in the PNW once were. My ears are BURNING from the AC/fanfest going on and I can’t believe it’ll persist into the weekend, even with 70s.

    Let’s all do our part, and let’s work on harsh punishments for human-caused fires. This is unacceptable!

  6. I was just going to ask if this was possibly the work of some disgruntled group. I know in Washington there was a statement made that all the new fires were human caused because there had been no lightning...

  7. Anyone setting these fires are enemies of civilization.


  9. I just listened to a clip of Inslee mentioning global warming. Foolish.

  10. Listen to Cliff, he’s trying to help you!! We’re in Florence on the central Oregon coast. This stuff moved in Monday night, Tuesday was awful and air quality was bad. There were pretty good sized ashes falling, the sky was red and it looked like Mars. Wednesday was far worse, our air quality was somewhere in the 500s at least. Visibility was bad, cars had their lights on and street lights came on. Several businesses closed for their employees health. Don’t go out in it if you have a choice.

  11. Folks, the fires in Oregon started from Labor Day weekend carelessness and an unprecedented high wind event downing power lines. Unattended campfires and things that would normally have been minor or no problem at all blew up. Regardless, the air here in Eugene is unimaginably bad. It appears this is headed north. Please prepare. it’s very unhealthy. The lack of communication from local officials about the health hazard has been astounding, but I guess it shouldn’t surprise me

  12. Got up before 5 this am, obviously worst smoke of the summer. I can see the moon so it is low down smoke. 6:30 I can just make out windows on houses across Sinclair Inlet in Manette. But all the way across the Inlet I can barely make out houses. Hunker down time!

  13. Looks like all we have to do is go up about 8 Km (5 miles), about the height of Mount Everest... Oh, wait, we'd have to breath oxygen out of a tank...

    More proof that the West is getting drier.

  14. Pineapple express... Please! We need you- Now!

  15. has some good info about air quality, though I read somewhere that data are only updated every 2 hrs.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

More Rain for the Northwest is Good News for Wildfires

After a very pleasant dry spell, another rainy period is ahead for the western side of the region and the Cascades on Friday and Saturday.  ...