textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1201 AM PDT Tue Sep 22 2026

- Warming trend begins today through Thursday

- Cooler conditions Friday into the weekend

SHORT TERM

Issued at 1201 AM PDT Tue Sep 22 2026 (Today and tonight)

Extensive stratus has flowed into the North Bay valleys, Monterey Bay region, Salinas Valley, Hollister area, and the East Bay west of the Berkeley Hills. Across the rest of the SF Bay Area, patches of stratus have developed near Livermore and north of San Jose, with further expansion expected through the pre-dawn hours. The cloud deck retreats back to the immediate coast late this morning into the early afternoon, but by the time it develops again tonight, the marine layer will be compressed, leading to uncertainty over just how far inland the clouds will go.

The cut-off low that gave us the last couple days of cooler temperatures is moving across the state with the center crawling through the Mojave Desert into the Great Basin. This allows for more zonal flow to come into the state and a warming trend to begin today, with high temperatures in the upper 70s to the middle 80s across the inland valleys, into the upper 80s in the far interior regions of the North Bay and southern Monterey County, the middle 60s to the middle 70s close to the Bays, and the lower to middle 60s along the immediate coast. A breezy onshore wind will develop in the afternoon and evening hours, with the strongest gusts of 20 to 30 miles per hour along the coast, through favored gaps and passes, and within the northern Salinas Valley.

As a quick side note, today will mark the autumnal equinox and the start of astronomical fall. At 505 PM Pacific time, the sun's apparent path on the Earth crosses the equator, giving us 12 hours each of sunlight and nighttime.

LONG TERM

Issued at 1201 AM PDT Tue Sep 22 2026 (Wednesday through Monday)

Slight ridging will develop over California over the next couple of days, and while the ridge axis quickly moves into the Intermountain West, the ridge influence will allow for further warming Wednesday and Thursday. High temperatures warm into the middle 80s to the middle 90s in the inland valleys, the middle 70s to the middle 80s close to the Bays, and the middle 60s to the lower 70s along the Pacific Coast. Pockets of Moderate HeatRisk are scattered across the interior regions, particularly near San Jose, the interior East Bay, and the Santa Lucia range. These pockets are not expansive enough to merit a Heat Advisory.

By Friday, a developing trough in the eastern Pacific comes into the West Coast, and a cooling trend will cause temperatures to dip near and below seasonal averages. Weekend highs range from the middle 70s to the middle 80s in the inland valleys and the middle 60s to the middle 70s close to the Bays. Temperatures will recover early next week as the trough flattens and ensemble model cluster analysis hints at a ridge developing somewhere within the western United States, although the exact impacts are not certain at this point.

AVIATION

(12Z TAFS) Issued at 427 AM PDT Tue Sep 22 2026

Solid marine layer push overnight leading to mostly MVFR to IFR conditions. Seeing some compression on the marine layer leading to some patchy fog and dz/ra being reported. Expect clearing/rolling back to the coast mid to late morning most areas. HAF and MRY will hold onto CIGS for most of the day. Tonight, N-S gradient increases so less conf for stratus N and E Bay. Overall conf is moderate.

Vicinity of SFO...Much more optimistic for the TAF as SE flow caused rapid drying/clearing earlier in the night. Still watching a bank of clouds due E of SFO inching W. Carrying a tempo for now, but conf is low on actual impacts to terminal.

SFO Bridge Approach...Similar to SFO. CIGs far E fringe of approach.

Monterey Bay Terminals...IFR with low cigs, br, and dz/ra through 18z-ish . A few hours of VFR this afternoon, but CIGs and MVFR/IFR return early tonight.

MARINE

(Today through Sunday) Issued at 427 AM PDT Tue Sep 22 2026

Fresh to strong breezes will prevail early Tuesday as a weak cold front sweeps through the region. Behind the front more widespread strong breezes will prevail this afternoon. The stronger winds will result in hazardous conditions for small craft. Northwest breezes and seas remain elevated through the week with a brief period of improved conditions Wednesday night into Thursday. By Friday, winds increase with building rough seas.

FIRE WEATHER

Issued at 434 AM PDT Tue Sep 22 2026

Solid marine layer coverage along the coast and Salinas Valley overnight. Sounding and profilers put the depth of the marine layer around the 2,000-2,500 foot range. Definitely some compression on the marine layer leading to drizzlefest around the area. Seeing some reduced vsby too, which may lead to patchy fog early this morning for crews departing ICP for Timber/Plaskett. Above the marine layer moderate to excellent humidity recovery for the most part with the driest conditions above 3,000 feet. Otherwise, still valid for a warming and drying trend kicking off Tuesday with temperatures up to 10 degrees above normal and areas of moderate HeatRisk Wednesday and Thursday. The marine layer will compress below 1,000 feet during this warm-up with nocturnal drying expected above it.

MM

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 5 AM PDT Wednesday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 3 PM this afternoon to 5 AM PDT Wednesday for Pigeon Pt to Pt Pinos 10-60 NM.