Wednesday brings coastal chill, but inland heat builds fast
Wednesday, May 7, delivered the coolest temperatures of the week across much of the Bay Area, thanks to a thick marine layer and the residual effects of a lingering upper-level low. Coastal locations like San Francisco, Pacifica, and Half Moon Bay remained cloaked in low clouds with daytime highs struggling to escape the upper 50s (around 14-15°C), while inland temperatures only modestly rebounded into the 60s and 70s (16–25°C).
But this cool spell is quickly unraveling. A narrow ridge of high pressure is expanding over California, while the upper low that brought gusty winds and cooler weather continues to weaken, paving the way for the first widespread heat wave of the season.
Thursday warms up the valleys ahead of Friday’s inland surge
By Thursday, expect temperatures to rebound across the East Bay, South Bay, and North Bay valleys, where highs will reach the upper 70s to low 80s (25–28°C). Meanwhile, the marine layer will again thicken during the early morning hours, stretching farther inland, but will retreat faster by midday, letting more sunshine reach interior zones.
Friday’s real warm-up targets East Bay and Central Valley
Come Friday, high pressure dominates, and with the upper-level disturbance fully faded, hot air will surge inland. Cities like Livermore, Antioch, and Concord are forecast to flirt with or top 90°F (32°C), marking the first significant heat event of the year for much of inland Northern California. The East Bay interior, especially, will heat up sharply, while coastal regions remain capped by the persistent marine layer, limiting highs to the 60s (16–20°C).
Triple-digit temperatures expected across the Central Valley
The Central Valley is on track to sizzle, with temperatures soaring into the mid- to upper 90s (35–36°C) on Friday. Some areas, including Fresno, Hanford, and Bakersfield, may even crack the 100°F (38°C) mark, particularly by Saturday, signaling that summer conditions are arriving early in California’s agricultural heartland.
Regional breakdown: Wednesday’s conditions by zone
San Francisco
Upper 50s (14–15°C) near Sunset and Ocean Beach, low 60s (16–17°C) elsewhere. Marine layer thickens overnight, with gusty winds up to 20 mph expected in the afternoon.
North Bay
Morning fog and clouds clear to sunny skies inland. Highs: low to mid-70s (22–24°C) in Santa Rosa, Napa, Vacaville. 60s (16–20°C) in Novato, San Rafael, Vallejo. Overnight lows in the upper 40s to low 50s (8–11°C).
East Bay
Concord, Walnut Creek, Livermore reach mid- to upper 70s (24–26°C). Oakland and Richmond stay cooler at upper 60s (around 20°C). Patchy fog returns overnight west of the Berkeley Hills.
Pacific Coast and Peninsula
Persistent cloud cover in Half Moon Bay and Pacifica holds highs to upper 50s (14–15°C). San Mateo and South San Francisco reach mid- to upper 60s (18–20°C). West winds gusty by late afternoon.
South Bay and Santa Cruz
Clear skies in the South Bay, with Mountain View, San Jose, and Santa Clara warming into the mid- to upper 70s (24–26°C). Santa Cruz coast stays cooler, upper 60s (around 20°C), with morning fog clearing in the afternoon.
