textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1202 AM PDT Tue Aug 25 2026

- Temperatures near to slightly below seasonal averages persist within the marine layer through Thursday

- Seasonably warm and dry conditions continue above 1000 feet

- Pattern change Friday into the weekend brings cooler temperatures and moderate potential for tropical moisture

SHORT TERM

Issued at 1202 AM PDT Tue Aug 25 2026 (Today and tonight)

Satellite imagery shows an expanding stratus layer below scattered high clouds, with low clouds present in the valleys of southern Sonoma County, the San Francisco Bay region, and down the Salinas Valley. Coastal drizzle has been observed at the office, and has been added to the grids tonight. The stratus deck is expected to continue developing into the SF Bay region through the night before retreating back to the coastal regions after sunrise.

After a slight dip in the temperatures yesterday, temperatures will tick upward today as the balance between troughing in the eastern Pacific and ridging over the Desert Southwest swings back towards the ridging influence. Temperatures range from the 80s into the middle 90s for the inland valleys, up to around 104 in the southern tier of Monterey County, the upper 60s to the lower 80s near the Bays, and the upper 50s to middle 60s along the Pacific Coast. Breezy onshore winds will develop this afternoon and evening, with wind gusts 20 to 30 mph along the coast and through favored gaps and passes. The marine layer will remain around 1000-1500 ft today, with warm and dry conditions above the marine layer inversion. See the FIRE WEATHER section for the implications for local fire weather concerns.

LONG TERM

Issued at 1202 AM PDT Tue Aug 25 2026 (Wednesday through Monday)

The ridging prevails into Thursday with temperatures in the middle 80s to the middle 90s inland and the 70s into the middle 80s near the Bays. A pattern change begins on Friday with upper level troughing developing over the West Coast, bringing cooler temperatures and breezier winds to the region. Temperatures in the inland valleys dip into the 80s for the weekend, and cool further with highs dipping into the middle 70s to lower 80s early next week. Even the warm spots of the interior Central Coast cool into the middle to upper 80s by Monday. The strengthening pressure gradient will allow stronger onshore flow to develop starting on Friday, with wind gusts of 25 to 35 mph expected along the coast, through favored gaps and passes, and within the northern Salinas Valley.

We continue to monitor an active tropical Eastern Pacific and its indirect impacts to the region. Tropical Storm Iselle continues to march northwestward off the coast of western Mexico, and a Tropical Depression has spun up for around a day or so before it gets absorbed into Iselle. In addition, our colleagues at the National Hurricane Center are tracking three potential development areas through the next week. None of these storms are expected to directly impact the state, but long-period swell generated by the intense winds within the storms is expected to begin arriving Friday into the weekend. The current forecast remains just below Beach Hazards Statement criteria, but this will get refined through the next couple of days. There's also an increasing chance that tropical moisture will impact the region during Friday and the weekend, with the model trend being to push the moisture plume farther up the coast into the Bay Area and Central Coast. The NBM continues to show a very low (below 5% probability), but non-zero, chance for thunderstorms during this period, and given the uncertainties surrounding eastern Pacific tropical weather, this setup bears continued monitoring.

AVIATION

(12Z TAFS) Issued at 431 AM PDT Tue Aug 25 2026

A robust marine layer was measured at ~1800ft with the KOAK 12z balloon with primarily IFR/LIFR conditions with the exception of KAPC, KSJC and KLVK. Mid/high level cloud cover likely helping to keep the latter three terminals in MVFR/VFR through mid-morning. Majority of terminals are expected to lift to VFR by late morning, with KMRY having a 30% chance of lingering past Noon PDT.

Vicinity of SFO...Should remain IFR through mid/late morning before lifting to VFR for the remainder of the day and evening hours. KOAK may see MVFR/IFR ceilings return soon after sunset with KSFO more likely around midnight.

SFO Bridge Approach...Similar to KOAK with timing of ceilings.

Monterey Bay Terminals...Marine layer is not as deep this far south, however LIFR ceilings are expected to persist through late morning, clearing out of KSNS first with KMRY possibly lingering into early afternoon with VFR until late afternoon early evening. IFR/LIFR conditions expected from that point on for the remainder of the forecast period.

MARINE

(Today through Sunday) Issued at 431 AM PDT Tue Aug 25 2026

Fresh breezes today will become fresh to strong on Wednesday and persist through the remainder of the week into the weekend with moderate seas. Long period southerly swell will begin to build on Thursday, becoming 15 to 17 seconds for Friday and Saturday, then begin to gradually ease on Sunday into next week.

FIRE WEATHER

Issued at 1202 AM PDT Tue Aug 25 2026

Near-critical fire weather conditions continue through Thursday for elevations above 1000 feet as warm and dry conditions continue across the region. Humidity recoveries remain poor to very poor in the higher elevations, with nocturnal drying expected within the Santa Lucia range. Breezy conditions will develop each afternoon and evening, but not for a long enough period to trigger any fire weather products. Specifically regarding the Timber Fire vicinity, observational data suggests that southwesterly winds from the Pacific Ocean over the ridgetops are helping to moisten the air, with nocturnal drying being observed as the winds diminish and even turn faintly offshore overnight. This has led to an unusual situation where daily maximum relative humidity values have been observed during the daytime. Smoke transport from the Timber Fire will continue to peak in the afternoon and evening with the plume spreading towards the Salinas area. Friday into the weekend, a pattern change should allow for some relief as an upper level trough comes into the region bringing cooler temperatures and a deeper marine layer.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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