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

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

(18Z TAFS) Issued at 1206 PM PDT Tue Aug 25 2026

Stratus quickly dissipated out of the remaining terminals and widespread VFR prevails this afternoon. Onshore winds should remain moderate throughout the day and ease to gentle overnight. Rather tricky stratus forecast this TAF period. Model guidance is trying to indicate a widespread compressed marine layer tonight into tomorrow, but it is not convincing when compared to observations. Per the OAK sounding this morning, the marine layer was measured at a depth of around 1700 feet. Closer to Monterey Bay, the marine layer is around 1200 feet. That being said, highest confidence for IFR to LIFR ceilings at HAF, MRY, and SNS around sunset. Low confidence on whether SJC will develop a ceiling as it depends on how deep the marine layer decides to be tonight. The other Bay Area terminals can expect IFR to low-end MVFR ceilings to arrive around or after sunset.

Vicinity of SFO...VFR with northwest breezes increasing to fresh through the afternoon and diminishing to gentle overnight. If the stratus pattern from this morning holds, IFR ceilings may develop shortly after sunset and dissipate by late Wednesday morning. The current TAF relies a bit on persistence from last night, but overall low to medium confidence on the exact timing.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the day as northwest winds remain around 10-12 kt. Stratus is expected to bring IFR ceilings around 7-8 PM PDT this evening as winds become light. Ceilings may drop to LIFR overnight which will reduce visibility due to either mist or fog. Stratus should clear by late Wednesday morning.

MARINE

(Tonight through next Sunday) Issued at 1206 PM PDT Tue Aug 25 2026

Moderate northwest breezes become fresh to strong Wednesday and persists through the week. Wind driven seas remain moderate into the weekend. A long period southerly swell around 15 to 17 seconds continues to build 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 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.