Saturday’s intense heat across California will be the last major surge before a dramatic cooldown sweeps through the state on Sunday, June 1, 2025. A high-pressure system currently holding much of Northern and Central California in a grip of dry, hot air is set to weaken quickly, opening the door to cooler marine air and a pair of low-pressure systems that will bring relief from the heat and potentially even thunderstorms in parts of Southern California.
Hot, dry Saturday across inland California
Inland portions of the Bay Area, including the interior East Bay valleys and the North Bay mountains, are forecast to climb back into the 90s °F (mid-30s °C) on Saturday, with heat advisories in effect from 11 a.m. to 8 p.m. Temperatures in the South Bay will be a bit more moderated, hovering in the upper 80s to low 90s °F (31–34 °C), thanks to increasing sea breezes expected by midafternoon.
Further inland, the Central Valley will endure even more intense conditions. Temperatures are forecast to peak between 101 and 108 degrees °F (38–42 °C) on Saturday, potentially matching or exceeding daily records in Merced and Hanford, both forecast to hit 105°F (40.5°C). The Sacramento Valley, especially areas east like Roseville, could near 105°F, while Red Bluff and Chico may touch 107°F (41.6°C).
Even San Francisco, often spared the heat, will feel a sharp split in temperatures due to its notorious microclimates. Ocean Beach may barely reach 60°F (15.5°C), while neighborhoods farther east in the city could top 70°F (21°C). Oakland is forecast to land just under 80°F (26.6°C).
Sunday cool-down: Big changes in Bay Area and Central Valley
On Sunday, a marked temperature drop is forecast statewide as high pressure collapses and low-pressure systems move in from both the Southern California coast and near the Oregon border.
Expect highs to dip to:
- 60s to low 70s °F (15–22 °C) near Bay Area shorelines
- 70s to low 80s °F (21–27 °C) in the interior East Bay and Wine Country
- Mid-80s to low 90s °F (29–33 °C) in the Sacramento Valley, notably 5 to 7 degrees lower than Saturday
This cool-down will also introduce more marine-chilled winds, helping stabilize temperatures that have hovered well above seasonal averages.
Storm potential in Southern California and the Sierra
While Northern California cools off, Southern California braces for a new weather twist. The low-pressure system offshore is expected to interact with moisture remnants from Tropical Storm Alvin, leading to an elevated risk of thunderstorms.
The Sierra Nevada and Mojave Desert may see scattered thunderstorm activity on Saturday, expanding into the Antelope Valley and Transverse Ranges by Sunday. Rain showers and isolated storms are likely across Southern California, with Palm Springs—which averages just 0.05 inches of rain in May—possibly picking up 0.10 inches (2.5 mm) or more.
Erratic wind gusts and dry or wet lightning strikes are possible across this region, signaling heightened wildfire risk alongside the rare moisture.
Stay tuned for updated forecasts as the weather pattern shifts rapidly over the weekend, breaking the heat and introducing the first signs of an early summer monsoon influence in parts of California.
