The National Weather Service is issuing an Air Quality Alert for Central and Eastern Washington which will expire on Monday morning. However, several counties will see relief sooner and NWS will end the AQA early for those locations as conditions improve. Sunday night and Monday morning will bring rain to Western Washington and other west-facing mountainous areas, but the eastern Cascades probably won't see much more than a sprinkle.
Much of Eastern Washington should expect air quality to vary from Moderate to Unhealthy today, but improve slowly through the weekend. Winds from the east have been bringing in smoke from BC and Montana fires, which hit Spokane yesterday and will continue to pester residents in Eastern Washington today. Winds should die down a little on Saturday but expect some smoke to linger potentially through Sunday. With the chilly temperatures, low mixing heights, and low winds on Saturday, there will be some smoke drainage into valley towns. Sunday will bring winds from the south and smoke should clear out then for much of Eastern Washington.
Central Washington air is still Unhealthy or worse, especially Klickitat, Kittitas, and Yakima counties. Hopefully this improves a bit through the weekend as fire activity reduces. Though, you may have to wait until the end of the weekend to see real relief, especially since smoke will continue to drain into the valleys from local fires. Some areas in Okanogan and Chelan counties will likely continue to see air that is Unhealthy for Sensitive Groups due to smoke from the Diamond Creek fire.
Clark and Skamania counties will continue to see smoke impacts from the nearby fires in Oregon through today. Most of the rest of Western Washington shouldn't see any smoke at the ground. Though, there is potential for a couple smoke plumes to pass overhead and potentially impact mountainous areas today as winds continue to blow from the east.
And now for the pretty picture: regional smoke seen this morning by the GOES-16 satellite.