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

(06Z TAFS) Issued at 940 PM PDT Mon Aug 24 2026

The marine layer is roughly 1,000 feet deep and well organized. As the marine layer makes its nightly push inland, IFR-LIFR conditions will be widespread across nearly all of the terminals through the night and most of the morning. The visibility is a little more uncertain, but some patchy fog is likely. Low clouds should start to clear for all but the coastal airports by late morning.

Vicinity of SFO...IFR ceilings have arrived and there is a high probability they will remain for at least the next 12 hours. There is a 40% chance that the visibility drops below VFR criteria after 10Z.

SFO Bridge Approach...Similar to SFO, although the ceilings haven't formed yet and they will clear earlier than the terminal Tuesday morning.

Monterey Bay Terminals...LIFR ceilings are essentially guaranteed through the night and most of the morning. While SNS will likely clear in the late morning, MRY may only see ceilings lift to IFR in the afternoon before dropping back down to LIFR Tuesday evening. If it does clear, it probably won't be for more than 6 hours.

MARINE

(Tonight through next Sunday) Issued at 917 PM PDT Mon Aug 24 2026

The increasing gradient between high pressure over the Eastern Pacific and lower pressure over California will cause winds to increase to a fresh NW breeze through the day tomorrow and winds will remain fresh to strong through the week. A long period southerly swell around 15 to 17 seconds 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 from 3 PM this afternoon to 9 AM PDT Wednesday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 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 9 PM this evening to 9 AM PDT Wednesday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.