Smoke lingers over North Bay, with air quality alert extended to Friday, but weekend conditions to improve

Raging wildfires across Northern California have funneled smoke into the Bay Area this week, resulting in unhealthy air quality in some areas of Sonoma County.

Regulators have extended their Spare the Air alert for the region into a second day on Friday.

However, conditions are expected to improve in the next few days as winds come to clear out some smoke and provide relief.

The 15 major wildfires burning across Northern California include the giant Dixie fire, which has burned over 678,000 acres across four counties — Butte, Plumas, Lassen and Tehama. Other infernos include the Monument fire, which has burned over 128,000 acres in Trinity County, the McFarland fire, which has burned over 111,000 acres in the Shasta-Trinity National Forest and the Caldor fire east of Sacramento in El Dorado County, which has burned over 65,000 acres.

Those four fires alone add up to over 983,000 acres, generating smoke that has blanketed much of Northern California, turning sunlight into a hazy orange hue day after day this week.

“Most of the smoke is aloft, thankfully,” said Cynthia Palmer, a meteorologist for the National Weather Service.

Still, the foul air presents a public health concern, especially for areas that tipped into one of two “unhealthy” categories. Spots across Sonoma County from Santa Rosa to the lower Russian River registered poor air quality Thursday afternoon, according to local sensors tied in to the PurpleAir network.

Official monitors from the Bay Area Air Quality Management District showed the air quality index for particulate matter, a main type of air pollution from fires, topping out in Sebastopol at 71, considered to be in the “moderate” category.

Although the smoke is aloft, creating a ceilinglike haze in the atmosphere, when temperatures warm, the smoke travels vertically and dips to the ground. That’s why residents can smell more smoke in the warmer hours of the day, said Bay Area Air Quality Management District spokeswoman Kristine Roselius.

Residents in higher elevations experience worse sustained air quality during such conditions because those high-elevation areas pierce the ceiling of smoke.

Most Sonoma County residents can expect moderate air quality with particulate matter in the low 60s, which means most people will be fine but sensitive individuals may want to take precautions.

“People should watch their air quality closely and if they smell smoke that’s a good indicator to stay indoors with windows and doors closed,” Roselius said.

A Spare the Air alert Thursday will continue into Friday due to deteriorating air quality during the hottest parts of the day around 1 to 2 p.m., according to Roselius.

A shift from offshore winds to onshore winds blowing from the ocean which will help push the smoke to the east and should improve air quality over the next 24 to 48 hours, Palmer said. Weekend forecasts show a return to good-to-moderate air quality for the Bay Area and Central Coast.

You can reach Staff Writer Alana Minkler at 707-521-5224 or alana.minkler@pressdemocrat.com. On Twitter @alana_minkler.