textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1231 AM PDT Wed Sep 30 2026

- Elevated fire weather conditions across the higher terrain through Thursday

- Areas of moderate HeatRisk across the interior through Tuesday

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

SHORT TERM

Issued at 1231 AM PDT Wed Sep 30 2026 (Wednesday through Thursday)

With ridging nosing in from the Eastern Pacific Ocean and a low across the Desert Southwest, the upper-level pattern will support northerly/offshore flow through Thursday. Northerly/offshore winds will be strongest during the overnight periods and in the higher terrain. Mt. St. Helena gusted to 48 mph Tuesday morning with gusts of 25-35 mph elsewhere, similar conditions can be expected during the overnight periods through Thursday morning. The combination of dry and windy conditions will result in elevated fire weather conditions across the higher terrain through Thursday. Temperatures will be 5 to 10 degrees above normal with the marine layer struggling to form. If it is able to form, it will be compressed around 500 feet and remain confined to the coast. Minor coastal flooding for bayshore locations along the San Francisco, San Pablo, and Monterey Bays will continue during the highest high tides through Thursday.

LONG TERM

Issued at 1231 AM PDT Wed Sep 30 2026 (Friday through Tuesday)

Global ensemble clusters are in agreement that anomalously high heights will be across our area through Tuesday. 500 mb heights and 850 mb temperatures are forecast to be near the 90th percentile for the first week of October, which is 588 decameters and 21 degrees Celsius, respectively. Saturday will likely be the peak of the heat as upper-level longwave ridging drifts in from the Eastern Pacific Ocean. Nonetheless, temperatures will be 10 to 15 degrees above normal with moderate HeatRisk away from the immediate coast through Tuesday. The marine layer will likely still struggle to form; if it's able to form, it will be compressed around 500 feet and remain confined to the coast.

AVIATION

(18Z TAFS) Issued at 1025 AM PDT Wed Sep 30 2026

Developing marine layer is battling building high pressure over the region. As such, the inversion height is compressed leading to low CIGs along the coast. That being said, expecting VFR through early this evening. CIGs return early for MRY/SNS and later for N Bay and in SF Bay. Moderate conf for fog development tonight given the shallow nature of the marine layer.

Vicinity of SFO...VRF through this evening. CIGs slowly redevelop inside SF Bay impacting OAK and SFO 07-09Z timeframe. Lower CIGs linger into the AM rush for Thursday.

SFO Bridge Approach...Less chc for late night CIGs, but still expecting some around the approach zone.

Monterey Bay Terminals...VFR through this afternoon, but CIGs lurking outside of MRY Bay will return early this evening. High conf on fog impacts by Thursday morning.

MARINE

(Today through Monday) Issued at 1025 AM PDT Wed Sep 30 2026

Northerly winds will continue to ease through the day, but still hazardous with moderate to strong breezes. Strongest winds are over the outer waters north of Point Reyes. Conditions will improve later this week and weekend as northwesterly breezes diminish to become gentle to moderate. Rough to very rough seas today will subside to moderate by Friday.

FIRE WEATHER

Issued at 502 AM PDT Wed Sep 30 2026

A high pressure system will move in from the west and compress the marine layer to approximately 500 feet. Hot and dry conditions will prevail through late week and weekend. Expect poor overnight humidity recoveries, with overnight relative humidities as low as 20-30% above the marine layer.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 5 PM PDT Thursday for CAZ006-506- 508-529-530.

PZ...Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.