textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1204 PM PDT Sat Sep 26 2026

- Cooler conditions through Sunday

- Warmer temperatures return Tuesday through the next week

SHORT TERM

Issued at 1204 PM PDT Sat Sep 26 2026 (This evening through Sunday night)

The stratus deck has mixed out to the immediate coast of Marin County and the Ocean Beach side of San Francisco and lurking near or just off the coast of San Mateo County. High clouds continue to flow over the North Bay and will continue to do so through the day, as the stratus deck returns to many of the coastal valleys this evening into the overnight period.

A developing trough with an axis around 600 miles west of Cape Mendocino is approaching the West Coast, digging deeper into the upper level flow as it does so and eventually dropping deep enough to cross into the California coast, where it should further develop into a cut-off low somewhere around the North Coast and the northern half of the Central Valley through the latter portion of Sunday. The influence of the cut-off low will bring cooler and more moist conditions to the region. High temperatures will range around 5 to 15 degrees below seasonal averages for today and Sunday, with highs in the inland valleys reaching the middle 70s to lower 80s today and the 70s on Sunday. High temperatures in the warmest portions of southern Monterey County will range from the middle 80s to lower 90s today, and the upper 70s to middle 80s on Sunday. Meanwhile, the Bayshore regions should expect highs in the upper 60s to upper 70s on Saturday and the middle 60s to middle 70s on Sunday, while the Pacific coast remains relatively cool with highs in the upper 50s to middle 60s on both days.

As the cut-off low moves across the state through the weekend, cooler temperatures and some incoming moisture should result in a wetter mid-layer, around the 300-500 mb layer. Exceedingly dry lower layers should cause the evaporation of most precipitation that may result, but can't rule out a few sprinkles overnight for the coastal regions and the highest peaks.

LONG TERM

Issued at 1204 PM PDT Sat Sep 26 2026 (Monday through next Friday)

Ridging should return to the region on Monday as the low moves into the Mojave Desert, setting up pushes of higher elevation offshore flow each morning from Monday to Wednesday, chiefly across the North and East Bay interior mountains. The strongest push looks to be on Tuesday morning with wind gusts of 25 to 35 mph possible in the interior mountains of the North Bay. The potential for wind gusts above 35 mph is greatest at the ridgeline of the Vaca Mountains along the eastern border of Napa County.

Otherwise, the arrival of the ridge should allow for temperatures to warm for the next week. By Tuesday, highs should reach the middle 80s to middle 90s in the inland valleys, the middle 70s to the middle 80s for the Bayshore regions, and the 60s to the lower 70s for the Pacific coast. These highs should basically remain stable through the rest of the 7-day outlook as ensemble model means and cluster guidance suggest that the ridging pattern should stick around in some shape or form into the upcoming weekend and possibly beyond.

AVIATION

(18Z TAFS) Issued at 1046 AM PDT Sat Sep 26 2026

Stratus is clearing rapidly across affected area terminal at this hour. VFR conditions expected prevail through this afternoon with a return of low clouds expected this evening over coastal terminals (KMRY and KHAF) and after midnight/early Sunday morning over inland terminals.

A short wave trough approaching the region tonight into Sunday will deepens the marine layer overnight. This may result in light rain or drizzle especially along the coast. However the relatively dry boundary layer may not allow it to reach the ground and may result in virga.

Vicinity of SFO...VFR conditions with scattered high clouds will prevail through the remainder of the day with moderate confidence that MVFR cigs will return overnight. Lighter winds than yesterday are anticipated. An approaching short wave trough will deepens the marine layer overnight resulting in the possibility of wet runways by morning due to light rain or drizzle.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR conditions will prevail through the remainder of the day with moderately high confidence that MVFR cigs will return this evening. Light to locally moderate onshore flow is anticipated. An approaching short wave trough will deepens the marine layer overnight resulting in the possibility of wet runways by morning due to light rain or drizzle.

MARINE

(Today through Thursday) Issued at 907 AM PDT Sat Sep 26 2026

Moderate north winds will persist through the remainder of the weekend increasing Sunday night into Monday becoming strong and gusty as a ridge of high pressure begins building in over the EPAC tightening the pressure gradient across the coastal waters. Strongest winds will be over the outer coastal waters accompanies by hazardous boating conditions.

FIRE WEATHER

Issued at 420 AM PDT Sat Sep 26 2026

Our diffuse cold front continues to slowly move southward through Southern California. In its wake, some areas have benefited from the cooler and slightly more "moist" conditions this morning. The exception, however, is across the higher terrain of the Santa Cruz Mountains as well as the Santa Lucia and Diablo Ranges where RH recovery remains poor (20-40%). Afternoon humidity will remain under 40%, largely for areas away from the coast. A push of onshore flow is expected later this evening into Sunday morning resulting in the marine layer deepening to around 2,000 feet ahead of an upper trough. This moisture push should diminish the areal coverage of poor RH recovery Sunday and Monday morning. A few sprinkles cannot be ruled out along the highest peaks associated with this upper low Sunday AM. Dry and modest offshore breezes will be a possibility Tuesday and into Wednesday, with the potential for wind gusts above 35 mph being greatest across the higher terrain of the North Bay in the wake of this upper low. Farther south across the Central Coast, the primary impact from this low will be a return to widespread poor RH recovery with some locales across the Santa Lucia Range struggling to see max RH above 30% Wednesday morning.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt to Pt Pinos 10-60 NM.