Bay Area heat spike in weather forecast

A late May heat wave could push parts of the Bay Area to near 100 degrees this week, baking the region’s landscape with some of the hottest temperatures of 2022 so far and setting the region up for a season dry fires.

High temperatures are expected to climb 5 to 20 degrees above normal on Tuesday and Wednesday for much of the Bay Area – part of a wave of hot weather that has triggered a heat advisory for the entire central valley and a red flag warning for a wide swath of northern California stretching from Vallejo to Redding.

Inner parts of the East Bay, including Discovery Bay and Livermore, could see temperatures hit 90 degrees and 100 degrees Tuesday and Wednesday, National Weather Service meteorologist Matt Mehle said. Peaks in the Santa Clara Valley are expected to peak in the 90s, including San Jose and Gilroy.

Temperatures are only expected to climb into the low 80s in Oakland — still 10 to 12 degrees above normal — while hitting the mid-70s in San Francisco.

Warm weather means the Bay Area can expect a high fire risk early this week, Mehle said. Humidity levels could drop to single digits in parts of North Bay and East Bay, while winds could blow 20 to 30 mph in parts of the East Bay Hills and Santa Clara County.

But forecasters have yet to issue red flag warnings for most of the Bay Area for those days, as recent storms in late spring helped pump enough moisture into the vegetation in the area to avoid the threat of major fires, Mehle said.

That should soon change, he added. This heat wave is expected to dry out grasses, shrubs and trees in the area, likely leaving dangerous fire conditions in June.

“After that, we will be in fire season,” Mehle said. “This period of warm, dry weather is going to basically help wash away any moisture we had from the late spring rains.”

Temperatures are among the hottest so far in 2022. San Jose, for example, has recorded just one day of 90-degree temperatures so far this year, according to the National Weather Service. The city reached 94 degrees on April 7 – just a hair higher than expected temperatures during this week’s heatwave.

The toasted forecast comes as firefighters completed work on two fires that prompted evacuations over the weekend in Solano and Mendocino counties.

Firefighters working on the Quail Fire outside Vacaville reported 90% containment early Monday morning, according to Cal Fire. The 136-acre blaze caused some residents to flee their homes on Saturday afternoon, although those evacuation orders were downgraded when crews brought the blaze under control. No cause has been announced for the fire.

The 36-acre Owens Fire was fully contained early Monday morning – ending a three-day fight to protect properties near Point Arena in Mendocino County, about 100 miles north of San Francisco. The cause of this fire is also under investigation.

Help is expected to arrive by Thursday, when the mass of high pressure over the Bay Area recedes and cooler temperatures return. The more moderate weather is expected to continue through Memorial Day weekend — meaning much of the Bay Area can expect highs in the 70s by Friday and Saturday.

“It’s going to be really nice,” Mehle said of the upcoming holiday weekend. “Temperatures will be much cooler and closer to seasonal averages.”

Dale D. Schrum