textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1200 PM PDT Tue May 12 2026

- Cooling trend continues today and Wednesday

- Elevated fire weather risk for far interior San Benito and Monterey counties this afternoon and evening

- Warming and drying trend resumes Thursday through the weekend

SHORT TERM

Issued at 1200 PM PDT Tue May 12 2026 (This evening through Wednesday)

The satellite imagery shows stratus coverage across the coastal regions and some lingering into the valleys of the Bay Area as a thin layer of high clouds persists over the region, with gradual clearing across the inland and Bayshore regions into the afternoon while the coast remains socked in. Stratus coverage should rebuild this evening and overnight but should not come as far into the southern Salinas Valley or the North Bay valleys as we saw this morning.

The large scale weather pattern features a departing ridge moving into the northern and central Rockies while a trough centered on an upper level low around 500 miles to the west of the Oregon Coast moves in, resulting in a gradual cooling trend today into Wednesday and an expansion of the marine layer. The latest readings from the Bodega Bay profiler suggest a marine layer around 1500-2000 feet thick, remaining rather consistent through the next couple of days as the trough passes through the region. High temperatures today will range from the upper 70s to the lower 80s in the inland valleys, the upper 80s to lower 90s in southern Monterey and San Benito Counties, the middle 60s to the middle 70s in the bayshore regions, and the upper 50s to lower 60s along the Pacific coast. Highs might be a few degrees cooler where the stratus is slower to dissipate than the forecast or does not clear out this afternoon. Low temperatures on Wednesday morning range from the upper 40s to the middle 50s across the lower elevations, while Wednesday's highs will range from the lower 70s to the lower 80s for the inland valleys.

As the trough moves through, the increasing pressure gradients will result in breezy and gusty winds starting this afternoon through Wednesday, with the gusts reaching 20 to 30 mph across the coastal and higher elevation regions and the northern Salinas Valley. Isolated favored regions, namely the Mayacama range and the Altamont Pass, may reach gusts of 40 to 45 mph this evening and overnight.

Elevated fire weather risks will set up starting this afternoon across a narrow strip of the far interior San Benito and Monterey counties adjacent to the Central Valley. A particularly concerning combination of gusty winds, hot temperatures, low daytime humidities, and poor overnight humidity recoveries across this region will result in a period of elevated fire weather concerns across this strip through the evening hours. Any fires that start in the drier grasses across this region may take hold and spread rather quickly. Our neighbors in Hanford have issued a Red Flag Warning for the adjacent zones across the western edge of Fresno County, but in our area of responsibility. the fire weather concerns are not widespread enough to warrant any products.

LONG TERM

Issued at 1200 PM PDT Tue May 12 2026 (Wednesday night through next Monday)

As the trough moves out, warmer and drier weather will return to the region with highs on Thursday and Friday in the 80s to the lower 90s in the interior valleys, the middle 70s to lower 80s across the Bays, and the lower to middle 60s in the Pacific coast. A second trough coming down from the Gulf of Alaska will interrupt the warming trend this weekend, with inland highs dipping in to the lower 70s to lower 80s on Saturday before bouncing back to the upper 70s to middle 80s for Sunday.

Uncertainty in the forecast starts to increase in the early part of next week as the ensemble models struggle to diagnose the interaction between an upper level ridge and trough over the western United States. Model ensemble means from the American GEFS, European ECMWF, and Canadian GEPS models suggest a ridge over the eastern Pacific and a trough over the Rockies should develop by Monday morning, although with significant differences in the strength of both features. However, a peek into the model ensemble clusters reveals a significant minority of the ensemble members (around 30- 40%) show an alternate scenario where more zonal flow or troughing develops over the West Coast, nudging the forecast towards cooler temperatures. Past the 7-day outlook, CPC outlooks into the later part of May show a slight lean towards temperatures above seasonal averages, and precipitation totals near or above seasonal averages.

AVIATION

(00Z TAFS) Issued at 443 PM PDT Tue May 12 2026

Gusty onshore winds will persist through a majority the TAF period for sites in proximity to the ocean/bay. Winds are expected to ease slightly after midnight for Bay Area terminals, but then increase again late morning into the afternoon on Wednesday for the remaining sites due to a dry cold front moving east across the northern portion of our forecast area. Guidance is confident on MVFR cigs developing after midnight and persisting through late morning Wednesday. The timing and coverage of IFR/LIFR cigs is low confidence, and if reached may not persist for long.

Vicinity of SFO...MVFR cigs are expected to develop by midnight and persist through late morning Wednesday and gusty onshore winds extending through the TAF period. An Airport Weather Warning is in place until 11pm PDT tonight for wind gusts reaching 40 MPH at times.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR cigs are expected to persist tonight through Wednesday morning at both KMRY and KSNS. There's more confidence in KMRY becoming IFR/LIFR after midnight and continuing through mid-morning Wednesday. KSNS is expected to clear out Noon with some partial clearing possible at KMRY by early afternoon.

MARINE

(Tonight through next Sunday) Issued at 443 PM PDT Tue May 12 2026

Hazardous marine conditions develop midweek and will continue into next week. Winds increase through the remainder of the week with strong to near gale force winds and occasional gale force gusts Wednesday and Thursday. Wind driven seas will build to between 10 to 12 feet Wednesday and Thursday. Surface high pressure will then strengthen over the eastern Pacific Friday into next week. This will result in a strong coastal jet, widespread gale force to potentially severe gale winds, and very high, wind driven seas between 12 to 17 feet expected.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.

Small Craft Advisory until 9 AM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 AM PDT Thursday for Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory from 9 AM Wednesday to 3 AM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory from 3 AM Wednesday to 9 AM PDT Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 9 AM Wednesday to 9 AM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10- 60 NM.