textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1240 AM PDT Mon Sep 28 2026

- Elevated fire weather conditions across the higher terrain through Wednesday

- Areas of moderate HeatRisk across the interior Wednesday through Sunday

- Minor coastal flooding for bayshore locations along the San Francisco, San Pablo, and Monterey Bays Monday through Friday

SHORT TERM

Issued at 1240 AM PDT Mon Sep 28 2026 (Monday through Tuesday)

An upper-level low will dig diagonally across the state Monday into Tuesday. Sensible weather wise, Monday will be the coolest day of the week with temperatures near to slightly below normal alongside onshore winds of 10-20 mph with gusts up to 30 mph. All signs point to the 2,000 ft marine layer mixing out, yet it prevails. The associated lift and accompanying wind from the aforementioned low will favor an earlier than normal clearing time of stratus (although it's more like stratocumulus out there). Of more impact is the northerly/offshore flow that will develop as upper-level ridging noses in from the Eastern Pacific Ocean in the low's wake. Wind speeds of 15-25 mph with gusts up to 35 mph can be expected across the interior higher terrain, especially the North Bay Interior Mountains and East Bay Interior Mountains. This will start tonight (Sunday night/Monday morning) and peak Monday night/Tuesday morning and Tuesday night/Wednesday morning. The combination of dry and windy conditions will yield elevated fire weather conditions for the higher terrain during this time. Tuesday and Wednesday will be warmer and drier from rising heights and northerly (drying) winds. Northerly/offshore flow will also minimize if not erode the marine layer, allowing the coast to warmup. Minor coastal flooding for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay during the highest high tide Monday through Thursday.

LONG TERM

Issued at 1240 AM PDT Mon Sep 28 2026 (Wednesday through Sunday)

Global ensemble clusters are in agreement that upper-level ridging with anomalously high heights will dictate our forecast Wednesday through Sunday. 850 mb temperatures above the 90th percentile will support temperatures 10 to 15 degrees above normal. As a result, areas of moderate HeatRisk are expected across the interior above and away from the compressed (<~1,000 ft) marine layer. No daily maximum temperature records are in jeopardy.

AVIATION

(12Z TAFS) Issued at 515 AM PDT Mon Sep 28 2026

The marine layer this morning is around 1500-2000ft, as evident by the expansive stratus deck across both coastal and interior valley locations. Drier air is still anticipated to work its way through the region today, which should lead to an earlier clearing of clouds this morning. After that, VFR conditions are expected to prevail with with onshore flow gradually becoming onshore.

Vicinity of SFO...Stratus and MVFR cigs are being observed this morning, with hi-res models showing clearing between 13-17Z. Once clear, VFR conditions should prevail and be accompanied with onshore flow. Models show another breezy afternoon and evening around SFO, with gusts up to 20-25kt from roughly 20-06Z. Onshore winds of less than 10kt are expected through the rest of the TAF cycle.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...The forecast looks to be on track this morning, with MVFR cigs holding around the region. Stratus should begin clearing the region between 16-18Z, which should lead to a stretch of VFR conditions. Opted to trend with a more optimistic forecast for the evening, as hi-res models over the last few runs have eased on the return of stratus tonight. Will need to keep an eye on it and see how the forecast pans out and if we're able to get any clouds as the marine layer settles to 500ft.

MARINE

(Today through Saturday) Issued at 252 AM PDT Mon Sep 28 2026

Moderate to strong north winds will continue through Wednesday with the strongest gusts across the northern outer waters and south of Point Pinos, where near gale force gusts are expected at times. Rough seas will build in response to these winds and will subside to moderate by the end of the week due to northerly winds becoming light to moderate. Tropical activity will produce long period swell up to 16 seconds Wednesday and Thursday.

FIRE WEATHER

Issued at 515 AM PDT Mon Sep 28 2026

The marine layer persists this morning, around 1500-2000ft, but should gradually compress to around 500ft throughout the day. Today will be coolest day of the week, though it is also the start of a warming trend. Offshore flow gradually works its way into the region today, which will lead to breezy winds each morning from through Wednesday. The strongest winds are expected on Tuesday morning in the interior mountains of the North and East Bays, where wind gusts could reach 30-35 mph. These offshore winds should contribute to poor overnight humidity recoveries, with overnight relative humidities as low as 20-40% above the marine layer.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory from 11 AM this morning to 5 PM PDT Thursday for CAZ006-506-508-529-530.

PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Wednesday for Pt Arena to Pt Reyes 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 until 11 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 PM PDT Wednesday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.