Bay Area heat wave to bring 100-degree temperatures miles from socked-in coasts

The Bay Area is expected to see a massive temperature swing between the coast and inland areas this weekend as a ridge of high pressure settles in alongside a resilient marine layer. 

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For days, high pressure has been building in the desert southwest, and now that weather pattern is currently expanding westward over California. This weather change is forecast to kick-start a heat wave Thursday in the Bay Area that could push temperatures into the triple digits in parts of the North Bay and East Bay through this weekend. 

National Weather Service meteorologist Dial Hoang told SFGATE there will actually be two periods of warming weather, with the hottest temperatures expected on Saturday and then Monday.

“Looking at places like Cloverdale, northeastern parts of Napa County and the far eastern part of Contra Costa County,” Hoang said, “that is where we might see temperatures rise into the triple digits.”

Certain areas could see multiple days of temperatures reaching or surpassing 100 degrees.

Starting Saturday, the Napa Airport could see three days of high temperatures breaking 100 degrees, while Vacaville is forecast to see temperatures hit 100 on Saturday and then rise to 102 by Monday. In the East Bay, Brentwood is forecast to hit triple digits starting Friday, with a high of 103 expected on Monday.

The sweltering weather won’t be felt across the entire Bay Area thanks to the marine layer, which is expected to hang on and keep coastal areas cool. 

“Along the Pacific coast, places like Half Moon Bay, Pacifica, we’re expecting temperatures around the middle 60s, maybe the upper 60s,” Hoang said. “At downtown San Francisco and Oakland, our warmest highs are expected to be around the middle 70s to the lower 80s.”

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On Thursday, the marine layer is expected to drop from a 1,000-foot wall down to 800 feet, and the high-pressure ridge is expected to shrink the layer further over the weekend. But even a diminished marine layer is expected to keep the hot weather at bay.

“Shallow compressed marine layer will keep the coast from seeing the real heat,” the weather service said in its forecast discussion. 

With the dry, hot temperature, the weather service warns fire weather will also be elevated in parts of the North and East Bay in the Diablo and Santa Lucia ranges.

Hoang said it’s not yet clear whether the marine layer will be able to hang on along coastal areas next week if high pressure persists and continues to shrink the fog.

“If the high pressure is strong enough, it could even disappear completely, and we can have warm temperatures all the way to the coast,” he said.