These images were captured in early afternoon on August 20, 2015. Notice how the smoke loops up into Canada before dispersing over the east side of the continental divide in Montana.
Note: Some users might notice intermittent discrepancies in colors shown on the map of air quality monitors above, and those reported on the Department of Ecology's official page. This is because Ecology believes their method of calculating the air quality category (i.e. “Good”, “Moderate”, Unhealthy” etc) is more protective of public health in Washington. If in doubt as to which better represents public health risk, use the more stringent of the two (i.e. the map showing worse air quality).