2 Days of Northern California Heat Kick Off After a Warm Night

Feeling a little hotter last night across the Bay Area?

According to the National Weather Service, that’s because temperatures in interior areas surged up to 20 degrees from Tuesday night’s highs — the start of a fast-moving warming trend that will affect the region in the back half of the week.

The overnight spike kicked off two days of heat expected to peak in the Bay Area on Thursday afternoon, bringing widespread highs in the 80s and even possible triple-digit temperatures in the Sacramento Valley and far Northern California.

While the weather could feel like a stark departure from recent weeks, weather service meteorologist Dylan Flynn said highs will really only be slightly above average for early July.

“The swing from early in the week to where we are now is pretty notable for this area,” he told KQED. “It’s maybe 5 to 10 degrees above normal for this time of year, [but] since it’s been cooler than average for June and July, it will feel quite a bit warmer than it’s been.”

Flynn said the Bay Area’s “natural air conditioning” — the cooling effects of the Pacific Ocean — has been in overdrive this year, thanks to a pocket of water just off the coast of California that’s a few degrees cooler than normal.

The phenomenon has led to a stark divide to start the summer, according to meteorologists and climate scientists: a coastal marine layer and cooler temperatures closer to the ocean, and near triple-digit heat in inland areas.

That’s been keeping the Bay Area fairly temperate, and aside from this week’s warm-up, the trend is expected to continue.

“I can’t find any indications that we have a heat wave coming in July or August,” Flynn said. “That could still change, but right now it looks like this kind of near normal, maybe even a little below normal, is going to be the story.”

Still, inland parts of the Bay Area could see their hottest temperatures so far this summer because the marine layer that usually cools the region is hugging close to the coast.

While that’s keeping highs on the west side of San Francisco, as well as coastal parts of the North Bay and Peninsula, in the upper 50s and low 60s, temperatures downtown and in inner neighborhoods of San Francisco could hit their summer peaks on Thursday, possibly getting into the high 70s.

The interiors of other Bay Area counties will hit the 90-degree range, with Livermore and the coast of Sonoma County getting the most intense heat.

Along the bay, temperatures are expected to hit the 80s.

Temperatures will drop slightly on Friday, but the Bay Area is expected to settle into a more normal range — slightly warmer than the last few weeks — over the weekend.

“When we get back to normal this weekend, for inland areas at least, it will feel warmer than it has,” Flynn said. Longer term, cool weather is expected to return.

In the Sacramento Valley and far north, hotter weather, and a moderate risk of heat-related illnesses, will persist through the weekend.