textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1243 AM PDT Sat Oct 3 2026

- Moderate to major HeatRisk across the Bay Area and Central Coast Saturday and Sunday

- Moderate to major HeatRisk across the interior Bay Area and Central Coast Monday through Thursday

- Elevated fire weather conditions across the higher terrain through Thursday

SHORT TERM

Issued at 1243 AM PDT Sat Oct 3 2026 (Saturday and Sunday)

The 00Z sounding observed an 850 mb temperature of 22.95 degrees Celsius and a 500 mb height of 5900 meters, both of these are above the 90th percentile. The heat will peak this weekend as an upper- level longwave ridge drifts in from the Eastern Pacific Ocean. A Heat Advisory will go into effect at 11 AM Saturday and run through 10 PM Sunday for most of the Bay Area and Central Coast. It was extended in area to include the Carmel Valley, Hollister Valley, Marin Coastal Range, Northern Monterey Bay, Northern Salinas Valley, and San Francisco. Now, the only places that are not included is the North Bay Coast, San Francisco Peninsula Coast, and Southern Monterey Bay; this is banking on a compressed marine layer keeping these spots cool. If the compressed marine layer is able to survive, expect reduced visibility from fog along the coast. If it is not able to survive, coastal conditions will be hotter than currently forecast. Moderate to major HeatRisk will result from maximum temperatures 10 to 20 degrees above normal. Minimum temperatures 10 to 20 degrees above normal with weaker than normal onshore flow will bring limited relief overnight, also contributing to HeatRisk. Even less relief is expected in the higher terrain where elevated fire weather conditions continue with hot and dry conditions, prominent thermal belting, and prolonged burn periods.

LONG TERM

Issued at 1243 AM PDT Sat Oct 3 2026 (Monday through Friday)

The Heat Advisory will remain in effect through 10 PM Monday for the interior Bay Area and Central Coast. Upper-level shortwave troughing will undercut the ridge and bring an increase in onshore flow Monday; however, the interior will remain hot. Global ensemble clusters are in agreement that heights will rebuild Tuesday and peak Wednesday. With little change in the day-to-day forecast and the cumulative heat impacts, we could be looking at an extended Heat Advisory. This is especially true for the East Bay and South Bay where major HeatRisk is likely (60%+) through Wednesday. The marine layer will remain compressed during this time, keeping the coast cool and likely reducing visibility from fog. Elevated fire weather conditions will continue in the higher terrain through Thursday for hot and dry conditions with prominent thermal belting and prolonged burn periods. Thursday remains uncertain on ridge vs. trough, but by Friday it is likely that heights will begin to fall.

AVIATION

(06Z TAFS) Issued at 1002 PM PDT Fri Oct 2 2026

VFR through the TAF period at most terminals with coastal sites having a higher chance of brief LIFR ceilings overnight. VFR conditions prevail across the region by Saturday morning with a lower chance for stratus to return tomorrow evening as the marine layer becomes more shallow. Medium confidence on the exact timing of LIFR ceilings at HAF and Monterey Bay terminals. Reductions to visibility are still possible at these sites, though confidence has decreased on the exact impacts and timing. Light onshore winds continue through the night, occasionally becoming variable due to a weak push of offshore flow. By Saturday afternoon, moderate onshore breezes around 7 to 12 kt prevail.

Vicinity of SFO...VFR through the TAF cycle. High clouds will continue to pass through the overnight hours. A brief bay breeze will settle in at SFO Saturday morning before shifting to its usual northwesterly flow with clear skies.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with light winds shifting between a northwest to easterly flow. Overnight, east to southeasterly breezes prevail with medium confidence on the arrival of LIFR ceilings. Looking at current satellite imagery (as of 10PM PDT), dry air is impacting the robustness of the marine stratus deck. If LIFR ceilings develop, they will be short-lived. Low to medium confidence on fog development at MRY. By Saturday morning, clear skies prevail as onshore winds increase to 5 to 10 kt.

MARINE

(Tonight through next Thursday) Issued at 1002 PM PDT Fri Oct 2 2026

North to northwesterly breezes remain gentle to moderate into early week, allowing for slight to moderate seas to persist.

FIRE WEATHER

Issued at 353 AM PDT Fri Oct 2 2026

Ridging will lead to hot and dry conditions across the region through the seven day outlook. Daytime humidity retention will remain poor to very poor away from the immediate coast, while overnight, the thermal belts remain active and humidity retention in the higher elevations is poor. Pushes of offshore flow are possible in the higher elevations each morning. Hazardous heat builds this weekend, particularly impacting fire crews across the interior mountains and the Santa Lucia range.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory from 11 AM this morning to 10 PM PDT Sunday for CAZ006-502-528-529.

Heat Advisory from 11 AM this morning to 10 PM PDT Monday for CAZ503-504-506-508-510-512>518.

PZ...None.