Smoke along the waterfront in Seattle in 2020. (MyNorthwest photo)
Despite the arrival of smoke over the weekend, the Puget Sound region’s air quality has remained largely unaffected.
Up until this last weekend, onshore winds had kept smoke out of Western Washington, with Central and Eastern Washington bearing the brunt of the state’s recent fires. At one point in recent weeks, even New York City, Philadelphia, Pittsburgh, and Toronto had more smoke from West Coast wildfires in their skies than any city west of the Cascades.
That changed last Friday, after a ripple in pressure patterns pushed smoke from fires in Northern California, Oregon, and Eastern Washington straight into Western Washington.
But while hazy conditions are expected continue in Western Washington’s skies, smoke passing is passing through with enough height to only lightly impact air quality in the lowlands.
“The air quality sensors measure AQ at the surface, which is why some maps show ‘green’ for the area, even though we can see the lofted haziness,” the National Weather Service explained on Twitter.
The NWS forecast for this week predicts hazy conditions to remain in the region through Wednesday, before cooler temperatures and showers move in between Thursday and Friday. Beyond that, significant air quality issues are not expected to occur “in the near term.”
Central and Eastern Washington
East of the Cascades, it’s a different story.
The impact of smoke is measured on a 0-500 scale known as the Air Quality Index (AQI), broken down into six categories: good (0-50), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300), and hazardous (300+). In Okanogan County — where towns like Winthrop are sandwiched between wildfires on either side of their borders — AQI readings currently range between 300-500.
Further east near the Grand Coulee Dam, levels are still hazardous, hovering in the low to mid 300s. Meanwhile, Spokane’s AQI ratings have consistently sat just short of 200.
An air quality warning remains in effect for Okanogan, Ferry, and Stevens counties.