Bay Area Spare the Air alert extended through Saturday

The arrival of unusually warm January air in the Bay Area has made the need for wood burning a little less than it might be, a bit of a fortunate circumstance given that it will be illegal for residents to do so until at least Sunday.

Two more Spare the Air alerts came calling from the Bay Area Air District on Thursday, adding to the one that already was in effect. The alerts will stay in effect at least through Saturday.

That’s three Spare the Air alerts in the first 16 days of 2026. The air district issued only four in all of 2025.

The air district cited concentrations of particulate matter — commonly known as smog — to be elevated to a level where it’s closing in on being unhealthy for those with respiratory or other health issues. The air district anticipates the air to remain in the moderately healthy range.

A build up of high-pressure in the lower part of the atmosphere has allowed a summer-like bubble to park itself over the region, a dynamic that meteorologists with the National Weather Service said does not give the pollution that causes smog a chance to escape.

That dynamic also has contributed to tule fog that covered the North Bay for much of Thursday morning and areas of the East Bay in Contra Costa and Alameda counties for part of it. That tule fog is expected to remain in those areas, though offshore winds from the east have helped keep most of the region clear of it, NWS meteorologist Karleisa Rogacheski said.

The areas that received it got a thick dose. Livermore had only a quarter-mile of visibility Thursday morning, as did Concord and areas in Contra Costa County east of it, according to the weather service. The tule fog in those areas was expected to be at least just as thick on Friday morning.

The fog burned off in Contra Costa and Alameda counties but did not do so in the North Bay, Rogacheski said. San Jose and other areas of Santa Clara and Santa Cruz counties were not affected by the fog, nor are they expected to be.

“It’s not what we saw last November,” Rogacheski said of the fog. “But it’s gonna have an impact.”

The influence of the high pressure that’s causing this unusual warming trend is not expected to dissipate until at least Saturday. High temperatures were expected to reach the high 70s along the Central Coast and low 70s in areas of the South Bay on Thursday and Friday, while hitting the mid-to-high 60s in Contra Costa and Alameda counties.

“There’s an upper-level low (pressure system) way off to the West,” Rogacheski said. “That’s eventually going to push the high pressure north and over us. The next pattern change we expect to see is mid-to-late next week. We don’t know if that will mean rain or an offshore (wind) event.”