Bay Area To Sizzle In End-Of-Summer Heat Wave, Followed By Dry Lightning Storm

SAN FRANCISCO BAY AREA, CA — A heat wave is arriving in the Bay Area during the last week of summer, followed by a chance for dry thunderstorms, all of which are elevating concerns for fire danger, weather experts said.

The three-day warm spell will bring gusty winds, tropical moisture and daytime highs in the 80s, with some areas reaching triple digits.

Weather officials said a building ridge that has shifted onshore will push temperatures about 10 degrees above normal throughout the Bay Area. Inland temperatures will see temperatures range from the mid-80s to the upper-90s with temperatures along the coast in the 70s to low 80s.

For example, San Francisco is likely to see an unusually high 82 degrees on Monday, while interior communities like San Rafael could heat up to 96, according to the National Weather Service.

For now, forecasters said an official Heat Advisory will not be necessary, but things could change as the week goes on. Forecasters said the heat will likely make working or recreating outside for an extended period of time "uncomfortable."

"Remember to remain hydrated with plenty of water and electrolytes, limit time outdoors during peak heating if possible, and never leave children or pets unattended in vehicles," the weather service urged.

The hottest temperatures are expected to hit on Tuesday, with "slightly" lower temperatures possible on Wednesday. Some of the hottest Bay Area temperatures could be felt in Walnut Creek and Pleasanton, where temperatures are forecast to rise to 100 degrees on Tuesday.

After midnight on Thursday comes a chance for thunderstorms, which could send dry lightning strikes in some areas through late Thursday morning, primarily across the Central Coast in Monterey County and southern San Benito County, the NWS said.

Above normal warmth is forecast thru Wed with pockets of Moderate HeatRisk increasing the chance for heat-related illnesses. Hydrate with plenty of water/electrolytes, limit daytime activities during peak heating, and never leave children/pets in vehicles unattended! #cawx pic.twitter.com/3BF1KJtkyK
— NWS Bay Area 🌉 (@NWSBayArea) September 14, 2025

"Given the warm and dry conditions over the next few days, leading into the potential for isolated elevated convection early Thursday into Friday, the risk for lightning-induced ignition and rapid fire
spread is certainly non-zero and should be monitored closely by
our partners," forecasters wrote Monday.

On Thursday evening, rain is possible throughout the Bay Area, but forecasters aren't expecting heavy showers. Rain totals aren't anticipated to exceed a quarter of an inch "for those locations that are fortunate enough to receive any rain at all," the NWS said

The chance for light rain will continue into Saturday.

Here are the highs expected on Tuesday across the Bay Area:

San Rafael: 96 degrees

Mill Valley: 92 degrees

Livermore: 97 degrees

Pleasanton: 99 degrees

Walnut Creek: 100 degrees

San Francisco: 82 degrees

Oakland: 85 degrees

Cupertino: 93 degrees

Redwood City: 95 degrees

Healdsburg: 93 degrees

Petaluma: 92

The news comes on the heels of a much more intense heat wave last month that brought triple-digit heat. Some isolated areas in the Santa Lucias rose up to the 110s, the NWS said.

The dramatic switch in weather comes after the Bay Area experienced its coldest start to a summer in decades. In fact, the National Weather Service Bay Area office dubbed July "No Sky July."

SEE ALSO: 'No Sky July': The Bay Area Is Experiencing Its Coldest Summer In Decades

On Sunday, July 27, the San Francisco International Airport recorded its coldest start to the summer since 1965.

In downtown San Francisco, the weather service measured the city's coldest half of a summer since 1982. Meanwhile, across the Bay Bridge, Oakland is experiencing its coldest summer since 1970 — the coldest on record for the city.

“It’s not record-breaking — but at this point, we’re looking anywhere from 20 to 30 years since we’ve had this cold of a summer,” Matt Mehle, a meteorologist at the National Weather Service, told the Los Angeles Times.

It appears that August reversed that trend.