Luma Prudente and David Carneiro kick around a soccer ball at Alameda South Shore Beach during a warm day in March. Highs will reach the upper 60s to mid-70s along the bay shoreline Monday, with inland spots nearing 90 degrees.
Carlos Avila Gonzalez/S.F. Chronicle
June will start with the Bay Area’s warmest weather of the week.
Weak high pressure will peak over Northern California on Monday, nudging temperatures upward after a cool and unsettled end to May. This will not be a major heat event, but it should be enough to compress the marine layer, improve afternoon clearing and push inland valleys well into the 80s. A few of the warmest spots in the East Bay and North Bay may briefly flirt with 90 degrees.
The coast and San Francisco will stay cooler and more complicated. Low clouds and fog are likely Monday morning, especially near the water, but the marine layer should be shallow enough for better late-morning and midday clearing. Some high clouds may also filter the sun at times, but Monday should still be the warmest day of the week across most of the region.
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The Bay Area will see one more warm to hot day Monday before temperatures normalize midweek.
Baron/Lynx
By Tuesday, the ridge weakens and the pattern flattens out. That should return the Bay Area to a more familiar early June rhythm: low clouds near the coast and bay in the morning, afternoon clearing inland and temperatures mostly controlled by the daily strength of the sea breeze.
Monday’s warmup also comes as June arrives and meteorological summer begins. May was not especially dramatic by weather standards, but it did leave behind two interesting signals: unusually mild nights and uneven rainfall.
What stood out in May
The month was not especially hot by afternoon standards. There were no major heat outbreaks across the Bay Area, and even the usual inland hot spots reached only 90 degrees a handful of times. Vacaville was one exception, with seven days at or above 90 degrees, a sign that the early season heat mostly set up just east of the core Bay Area.
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The more notable signal came at night. Average lows ranked much higher than average highs at several Bay Area stations, including Half Moon Bay, Redwood City, San Jose, Napa and Santa Rosa. In many cases, the warmest May nights have clustered in recent decades, fitting a broader pattern of reduced overnight cooling that is strongly tied to climate change.
Rain was uneven, too. May included a couple of widespread light-rain events, then ended with a more focused late-month burst that dropped 0.60 of an inch in downtown San Francisco on May 28, setting a daily rainfall record for the date. But the month was not broadly wet. Most of the Bay Area stations reviewed still finished below normal for May rainfall, a small-scale version of the precipitation whiplash that has defined much of 2026: long dry stretches interrupted by brief, but very wet, storm systems.
Monday breakdown
San Francisco: Low clouds and fog are likely Monday morning, especially in the Sunset, Richmond District, Ocean Beach and near the Presidio. The marine layer should be shallow enough for better late-morning or midday clearing, but the immediate coast may stay partly cloudy and cool. Along the water, temperatures will top out in the low 60s, maybe a few degrees higher if the clouds clear. Highs will be in the low to mid-70s downtown, in the Mission District and toward Mission Bay. West to northwest winds at 10 to 20 mph will pick up during the afternoon, with low clouds returning Monday night and lows in the low 50s.
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North Bay: Monday will be hot in parts of the North Bay, especially away from the immediate bay shoreline. Morning clouds may briefly reach parts of Marin and the lower valleys, but clearing should be quick, with mostly sunny skies by late morning. Highs will reach the mid-80s in San Rafael, Vallejo, Napa and Petaluma and upper 80s to around 90 in Santa Rosa, Healdsburg and Vacaville. Winds will turn west to southwest during the afternoon, but won’t be noticeable beyond the immediate coast and around San Pablo Bay. Low clouds may return late Monday near the bay and Marin coast, with lows mostly in the low to mid-50s.
East Bay: Monday will bring a sharp west-to-east temperature spread. Morning clouds are likely around Richmond, Berkeley, Oakland and Alameda, but they should thin by late morning or midday, with filtered sunshine through high clouds during the afternoon. Highs will reach the upper 60s to mid-70s along the bay shoreline, including Richmond, Berkeley, Oakland and Alameda, with mid- to upper 70s possible in Hayward and Fremont. Farther inland, Concord, Walnut Creek, Pleasanton, Livermore and Antioch should climb into the upper 80s to near 90 degrees. West to southwest winds will increase during the afternoon, especially through the Interstate 580 and Highway 4 corridors and toward the delta. Low clouds may return near the bay Monday night, with lows in the 50s.
Pacific Coast and Peninsula: Monday will start with patchy low clouds and fog near the coast, but clearing should be better than it was during the grayer stretches of late May. Pacifica and Half Moon Bay should reach the mid-60s, while Daly City climbs close to 70 degrees if clouds clear early enough. Temperatures will rise quickly just a few miles inland, with South San Francisco and San Bruno in the low 70s, San Mateo in the mid-70s and Redwood City reaching the low 80s. Some high clouds may filter the sun during the afternoon, but they should not prevent Monday from being the warmest day of the week. West to northwest winds will increase later in the day, with low clouds returning Monday night and lows in the 50s.
South Bay and Santa Cruz: Monday will be the toasty across the South Bay, with morning clouds limited mostly to the Santa Cruz coast and nearby valleys. San Jose, Sunnyvale, Mountain View and Cupertino should warm into the low to mid-80s, while Morgan Hill and Gilroy climb into the upper 80s and possibly near 90 degrees. Santa Cruz should be cooler but still mild, with highs in the upper 70s. Clouds will be low near the water overnight, with lows in the 50s.
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