https://www.mercurynews.com/2020/09/15/air-quality-readings-improve-around-bay-area-as-hope-takes-shape-in-new-air-mass/

Something unusual hung in the air above the Bay Area on Tuesday morning, as the sun strained to show itself through the haze-filled sky that has become the new normal for the region:

“We’re starting to see the initial approach of a new air mass,” National Weather Service meteorologist David King said Tuesday. “It’s really headed toward the Pacific Northwest, but it’s creating a southwesterly flow, and that’s likely to push some of the smoke away.”