Record-Breaking Heat Wave Sweeps Across California, Bay Area to See Relief This Weekend

A heat wave is impacting California, with record-high temperatures expected in several cities. Even as Southern California braces for continued heat through Sunday, the Bay Area will experience a cooling trend starting this weekend.

Peak Heat and Potential Records

Thursday, March 19, 2026, is expected to be the peak of the heat in the Bay Area and potentially the hottest day of the year so far for San Francisco, offering a final chance to break the all-time March temperature record of 87 degrees. Inland valleys of the East Bay and South Bay are forecast to reach the mid to upper 90s for the third consecutive day.

Several cities are poised to break records:

• San Jose: Forecast at 92 degrees, exceeding the March record of 89 degrees set in 2015.
• San Rafael: Expected to reach 92 degrees, surpassing a record from 1964.
• Livermore, Redwood City, and Napa: All on track to break records dating back decades.

The Science Behind the Cool Down

The shift in weather is attributed to a thermal trough – a common occurrence in California during spring and summer, though somewhat unusual for March. Multiple days of extreme surface warming in the Central Valley and desert interior create a low-pressure zone. This deepens the pressure contrast with the Pacific, pulling cooler marine air onshore. Unusually cool sea surface temperatures off the Bay Area coast will further enhance the marine layer’s return.

Cooling Trend Over the Weekend

By Saturday, inland valley temperatures are predicted to drop by 10 degrees into the 80s. Sunday will bring another cooldown, returning temperatures to the 70s inland and 60s along the coast. Increased winds and the re-emergence of morning fog patterns are also expected.

Regional Breakdown – Thursday’s Forecast

• San Francisco: Very hot, potentially the hottest day of the heat wave. Temperatures expected in the low 90s in Noe Valley and the Mission District, upper 80s downtown, and 60s-70s in the Sunset District, Outer Richmond, and Presidio.
• North Bay: Sunshine and hot temperatures, with highs in the mid to upper 80s in San Rafael, Novato, Napa, and Sonoma, and low 90s in Santa Rosa and Petaluma.
• East Bay: Likely the hottest day of the week, with highs in the low 90s in Richmond, Oakland, Berkeley, and Hayward. Walnut Creek, Dublin, and Livermore will be similarly hot.
• Pacific Coast: Possible morning clouds along the coast, giving way to sunshine and record-breaking temperatures. Half Moon Bay could reach the mid-80s, setting a novel monthly record.
• Peninsula: Uneven warming, with South San Francisco and SFO in the 70s initially, rising to the mid-80s in the afternoon. Millbrae, San Mateo, and Redwood City expected to reach the low 90s.
• South Bay: The hottest region, with highs easily reaching the low 90s in San Jose and Santa Clara, and the mid-90s in Gilroy.

Southern California Remains Hot

While the Bay Area will experience relief, Southern California will continue to face above-normal temperatures through Sunday, with some easing expected as the high-pressure system shifts inland.

Source: San Francisco Chronicle