textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1242 PM PDT Tue Aug 25 2026

- A shallow marine layer will keep coastal conditions near normal through Thursday

- Seasonably warm and very dry conditions continue above 1000 feet and across the far interior through Thursday

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

UPDATE

Issued at 836 PM PDT Tue Aug 25 2026

Stratus is beginning to develop at the immediate coastal regions with high clouds flowing over the region. Some uncertainty remains over the extent of the stratus tonight, particularly regarding a possible compression of the marine layer that has not been observed as of yet, but will continue to monitor observations through the evening.

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SHORT TERM

Issued at 1242 PM PDT Tue Aug 25 2026 (This evening through Wednesday night)

Regional satellite imagery is showing stratus retreating to the immediate Pacific coastline with abundant sunshine expected across the interior this afternoon. Meanwhile, passing high clouds also persist and are moving northeastward across region. Thus, interior temperatures will warm into the 80s to mid 90s and up to around 105 deg F in the warmest interior parts of Monterey County. Persistent onshore and a shallow marine layer will keep temperatures near seasonal averages near the coast. Breezy onshore winds are forecast to develop by this afternoon and evening, with gusts up to 20 to 35 mph along the coast and in the favored valleys and passes.

Tonight, expecting stratus to return inland late this evening and into the interior valleys by Wednesday morning. However, the inland extent may be less than previous days as the marine layer compresses slightly.

For Wednesday, a slight up tick in temperatures as the ridge builds further west across the Desert Southwest. As such, temperatures will be some 5-10 degrees F above average with 10-20 degrees F above average in the far interior and higher elevations above 1000 feet. We are still expecting warm and very dry conditions above the marine influences with little to no overnight humidity recoveries through Thursday. See the FIRE WEATHER section for the implications for local fire weather concerns.

LONG TERM

Issued at 1242 PM PDT Tue Aug 25 2026 (Thursday through next Monday)

Afternoon temperatures will be slightly cooler on Thursday as a trough of low pressure approaches the West Coast, however 850 MB temperatures will remain between 23-26 degree C. The cooling trend will become more noticeable Friday and moreso into the upcoming weekend and early next week as the trough deepens over the Pacific Northwest. Thursday night into Friday, we are expecting mid/upper level tropical moisture to advect northward across the Bay Area and Central Coast. This will definitely increase high cloud cover and also result in an increased potential for high-based rain showers and/or thunderstorms. However, the lack of instability looks to be the limiting factor for thunderstorms. We are monitoring this closely at this time.

Expecting breezier conditions with the deepening trough off of the West Coast. Gusts are forecast to be between 25 to 35 mph near the coast and in the favored valleys, gaps, and passes by Friday and into the weekend. By Monday, temperatures are forecast to be some 5-15 degrees F below seasonal averages which matches with the CPC's 6-10 Day Temperature Outlook.

AVIATION

(00Z TAFS) Issued at 443 PM PDT Tue Aug 25 2026

The stratus deck remains off the immediate coast at this hour with an onshore flow eager to help usher it back to the coast this evening and into the overnight hours. We are anticipating the return of coastal low clouds tonight with limited inland intrusion through the gaps and bays as the marine layer will remain moderately shallow between 1000-1500 feet. IFR to LIFR cigs already impacting HAF with cigs expected at MRY, and SNS around sunset. Low confidence on whether SJC will develop a ceiling.

Vicinity of SFO...VFR conditions prevail with moderate west winds. Winds will ease becoming light overnight. IFR cigs expected to develop overnight with moderate confidence on timing.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions prevail with moderate west winds. Winds will ease becoming light overnight. IFR cigs expected around sunset this evening. Cigs expected to drop to LIFR overnight with reduced visibility. Clearing forecast between 18-19z Wednesday morning.

MARINE

(Tonight through next Monday) Issued at 836 PM PDT Tue Aug 25 2026

Moderate northwest breezes with strong gusts continue tonight as moderate wind driven seas prevail through the week. Northwest winds become fresh to strong Wednesday into the weekend. A long period southerly swell approaches our coastal waters by the end of the 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 until 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 until 9 AM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.