What is the expected duration of the smoke in the SF Bay Area? – Hot

Eye-stinging wildfire smoke blanketed the San Francisco Bay Area on Tuesday, and the National Weather Service said the gross air could stick around into Friday, perhaps longer.

“Looks like this smoke will linger for the next few days, with some short bits of reprieve,” said Dalton Behringer, a forecaster with the weather service’s Bay Area office in Monterey. “It looks like we’ll have a shift in the wind about midday Friday, and that will bring a period of relief. After that, there’s a trough from the Gulf of Alaska. That could bring more smoke in, but it’s hard to say, as we don’t know what the fires will do.”

Behringer added that the wind forecast is subject to change, and the fire’s behavior can also change and impact the amount of smoke the region receives.

Northwesterly winds aloft in the atmosphere, up to 2,000 to 5,000 feet above Earth’s surface, are carrying the smoke from far Northern California and southern Oregon into the San Francisco Bay Area. Behringer said that oftentimes, the smoke can stay high in the atmosphere above the marine layer, but Tuesday, the layer dissipated when afternoon temperatures warmed, which allowed the smoke to mix with Earth’s surface.

The smoke was especially thick in San Francisco late Thursday afternoon, and Behringer said that’s because some of the smoke was carried along the coast over the ocean, and then the sooty air was pushed directly into the city by the ocean breeze.

The Bay Area Air Quality Management District issued an air quality advisory due to the smoky conditions for Tuesday and Wednesday. This is a less severe warning than a Spare the Air Alert, which is issued when air quality conditions exceed federal standards. The district advised people to go indoors and close windows if they smell smoke.

Air quality is measured on an index that runs from 1 to 500, with readings of 1 to 50 indicating “good” air quality and 301 to 500 indicating “hazardous.” AirNow, a website that reports air quality based on readings from sensors monitored by the federal Environmental Protection Agency, showed air quality in the Bay Area falling within the “moderate” (51 to 100) to “unhealthy” (151 to 200) range, as of 7 p.m. 

The smoke is drifting from several fires burning in far Northern California and southern Oregon. Radar showed a lot of the smoke coming from the Anvil Fire in Oregon and the 2023 SRF Lightning Complex and Redwood Lightning Complex that spans Del Norte and Humboldt counties in California, Behringer said.

This breaking news story has been updated.