textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1237 AM PDT Fri Oct 2 2026

- Moderate to major HeatRisk across the interior through Thursday

- Elevated fire weather conditions across the higher terrain through Thursday

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

SHORT TERM

Issued at 1237 AM PDT Fri Oct 2 2026 (Today and tonight)

The 00Z sounding observed an 850 mb temperature of 21.75 degrees Celsius and a 500 mb height of 5900 meters; both of these are above the 90th percentile of 20.6 degrees Celsius and 5883 meters, respectively. Upper-level ridging across the Southwest will bring temperatures 10 to 15 degrees above normal to the interior Friday, resulting in areas of moderate HeatRisk. Subsidence aloft will compress the marine layer, keeping it confined to the coast and supporting fog development. Above the marine layer in the higher terrain, elevated fire weather conditions continue from hot and dry conditions with offshore flow overnight. Minor coastal flooding for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay will occur during high tide Friday afternoon.

LONG TERM

Issued at 1237 AM PDT Fri Oct 2 2026 (Saturday through Thursday)

A Heat Advisory is in effect for most of the interior from 11AM Saturday through 10PM Sunday. This covers the peak of the heat as upper-level longwave ridging drifts in from the Eastern Pacific Ocean. A compressed marine layer around 500 feet is currently forecast during this time; however, if it erodes from offshore flow or clouds fail to develop, the coast will be hotter than forecast. Upper-level shortwave troughing will undercut the ridge Sunday into Monday with the ridge rebounding across the West Coast Tuesday into Wednesday. No matter how you slice it, it is going to be hot for the next week with temperatures 15 to 20 degrees above normal and moderate to major HeatRisk across the interior. A compressed marine layer, weaker than normal onshore flow, and minimum temperatures well above normal will bring less relief than normal overnight. This will also keep elevated fire weather conditions across the higher terrain. Even though we are nearing the end of our heat season, cumulative heat impacts are expected across the interior. With all that being said, no records are in jeopardy as October is one of the hottest months for the region. Finally by Thursday, 44% of global ensemble clusters begin to show signs of a pattern change via falling heights.

AVIATION

(12Z TAFS) Issued at 442 AM PDT Fri Oct 2 2026

Similar to Thursday morning, conditions vary from VFR inland to stratus and fog /IFR-LIFR/ along the coastline, in the coastal and inland valleys. A fair amount of cirrus and perhaps some mid level clouds are moving up from the southwest associated with upper level divergence with the merged subtropical jet and southern branch of the polar jet. These clouds are currently obscuring much of the view of stratus and fog coverage; the high clouds will be with us through today. This may delay incoming solar radiative warming and delay stratus and fog erosion during the morning. Buoy and coastal surface observations show a fair amount of cool air entrenched within the marine layer, the marine layer is currently still ~ 1,000 feet deep. Additional stratus and fog can be seen on satellite moving southward from northernmost California. The nearest term is a challenging forecast because of this complex interaction that may lead to a blending of stratus and fog within a coastal surface trough with onshore winds by afternoon. Recent (06Z) HRRR output showed coastal stratus and fog /IFR-LIFR/ continue tonight and Saturday morning; tonight and Saturday are a long time from now with respect to stratus and fog forecasting and TAFs. Sometimes it can be difficult to disrupt stratus and fog in October without well structured offshore winds, downsloping and drying. The larger scale pattern is not conducive to widespread offshore winds like it can be in October; have to approach stratus and fog forecasting a day at a time since it's complex.

Vicinity of SFO...VFR except tempo stratus /IFR/ 13z-16z this morning. Stratus /IFR/ likely returns tonight and Saturday morning 10z-18z. Cirrus and perhaps some mid level clouds arrive from the southwest today, caveat is these clouds may slow stratus development and mix out today. Light west wind during the morning, shifting to northwest and westerly 10 to 15 knots in the afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus and fog /IFR-LIFR/ during the morning, conditions improving to MVFR-VFR by late morning or afternoon. Stratus and fog /IFR-LIFR/ return tonight and Saturday morning. Light and variable winds except cool air drainage winds 5 to 10 knots e.g. in the Salinas Valley during the morning. Winds shift to onshore 10 to 15 knots in the afternoon and early evening. Cool air east to southeast drainage winds redevelop tonight and Saturday morning.

MARINE

(Today through Wednesday) Issued at 353 AM PDT Fri Oct 2 2026

A gentle to moderate northerly to northwesterly breeze will continue through the weekend and into next week.

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...Coastal Flood Advisory until 6 PM PDT this evening for CAZ006- 506-508-529-530.

Heat Advisory from 11 AM Saturday to 10 PM PDT Sunday for CAZ503- 504-508-510-512>518.

PZ...None.