Smoke from Kincade Fire spreads across Bay Area

A photo take on Oct. 26, 2019, shows the smoke over San Francisco Bay as the Kincade Fire rages nearby in north Sonoma Countyl A photo take on Oct. 26, 2019, shows the smoke over San Francisco Bay as the Kincade Fire rages nearby in north Sonoma Countyl Photo: Addison Olian Photo: Addison Olian Image 1 of / 140 Caption Close Smoke from Kincade Fire spreads across Bay Area 1 / 140 Back to Gallery

A raging wildfire in north Sonoma County is pumping out smoke, and on Friday shifting winds pushed the sooty air into the greater Bay Area, reaching as far south as Monterey and as far east as the Sacramento and San Joaquin valleys. The smoke will continue to spread southward into urban areas on Saturday, with the worst air quality in the North Bay near the fire area

At 9 a.m. Saturday, air quality conditions in large swaths of the Bay Area were "moderate" on the Air Quality Index that measures pollution levels and health concern. At this level, some pollutants may be a moderate health concern for a small number of people.

The Bay Area Air Quality Management District forecasts levels will deteriorate to "Unhealthy for Sensitive Groups" in some locations around the Bay Area on Saturday. At this reading, members of sensitive groups may experience health effects.

Spencer Tangen with the National Weather Service said the smoke is likely to be worst in the morning and early evening with a break in the afternoon, but this forecast may change with the slightest shift in winds.

"This will depend on the exact wind direction that develops this afternoon and how much the fire is still going at that point," Tangen says.

Late Saturday night and into Sunday, winds are expected to shift to northeasterly and pick up in speed, pushing smoke out to the Pacific Ocean. The Air Quality District forecasts "moderate" conditions in the central Bay Area on Sunday.

Heads Up, Bay Area! Although the #KincadeFire isn't causing smoke issues over the Bay Area today, shifting winds tomorrow will likely cause the smoke to be directly over much of the region. Impacts to SFO may begin as early as 11am Friday. pic.twitter.com/3tlCIXIC5r — NWS CWSU Oakland (@NWSCWSUZOA) October 24, 2019

The Kincade Fire northeast of Geyserville has scorched 25,455-plus acres with 10 percent containment; visibility and air quality in the immediate area is poor with smoke concentrated in north Sonoma County.

Kristine Roselius, a spokesperson for the Bay Area Air Quality Management District, expects the Air Quality Index (AQI) across the Bay will fall within the low "Unhealthy for Sensitive Groups" levels (AQI scale) at times during the fire.

"This is similar to a cold, winter day when we have a temperature inversion and wood smoke builds up over the region," she explained. "We can’t forecast smoke levels beyond tomorrow at this point because there are too many variables (fire containment, unexpected wind shifts, etc.). The public can likely get information about clean air spaces from their County of Emergency Services but that may vary by county."

With the possibility of smoke spread, the Air District has issued a Spare the Air Alert for Saturday and is encouraging residents to avoid driving.

"We’re letting people know we expect air quality to be unhealthy," Roselius said. "We’re letting people know they should follow instructions from their local health officials."

For hourly air quality readings, visit the Air District’s website at: https://bit.ly/2p7UFgs.

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Amy Graff is a digital editor with SFGATE. Email her at agraff@sfgate.com.