textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1250 PM PDT Mon Aug 31 2026

- Well below normal temperatures through Friday, gradual warming and drying trend this weekend

- Beneficial wetting rain in the North Bay Tuesday through Thursday, drizzle/light rain possible elsewhere

SHORT TERM

Issued at 1250 PM PDT Mon Aug 31 2026 (Monday through Friday)

Upper-level shortwave troughing will swing into Northern California tomorrow; this will result in temperatures well below normal, a chance for drizzle/light rain, and widespread cloud cover. The best chances for drizzle/light rain will be in the North Bay, particularly along the coast and in the higher terrain with the help of orographic lift. A reinforcing upper-level low and an attendant cold front will approach the area Wednesday into Thursday. This will keep well below normal temperatures and cloudy conditions around and likely make the marine layer arbitrary. There will be a better chance for drizzle/light rain with this round with a lifting mechanism in place as PWAT climbs to near one inch (90th percentile). It is likely (60+% chance) that the northwestern half of the North Bay gets wetting rain (0.10 inches) between now and then. While rainfall is expected to be beneficial, wet roadways will create slick driving conditions and increase stopping distance.

LONG TERM

Issued at 1250 PM PDT Mon Aug 31 2026 (Saturday through Sunday)

Global ensemble clusters diverge on solutions dramatically going into the weekend, specifically on low vs trough and the location and timing of the feature, so basically everything. What is certain is that the region will be under the influence of some kind of troughing through the weekend. As it weakens through the weekend, a gradual warming and drying trend will commence with temperatures moderating to slightly below to near normal. Beyond the seven day forecast and into Labor Day/early next week, Invest EP95 well offshore of Southwestern Mexico becomes a variable. Uncertainty over the weekend will compound and propagate into the tropical side of the forecast, making it impossible to talk specific impacts at this point in time. The primary impacts would likely be rain and wind with impacts likely decreasing from south to north.

AVIATION

(00Z TAFS) Issued at 514 PM PDT Mon Aug 31 2026

VFR everywhere expect for HAF, SFO, and OAK where MVFR ceilings prevail. Marine stratus is expected to make another push this evening with MVFR ceilings developing at most terminals during the post-sunset hours and overnight. Low to medium confidence on the onset times for MVFR ceilings given the current stratus feed over the ocean is rather disorganized. Diurnal onshore winds persist through the TAF period with APC and LVK continuing to experience gusts around 20 kt this evening. Stratus is expected to scatter out late tomorrow morning into the early afternoon.

Vicinity of SFO...MVFR ceilings prevail through Tuesday morning with moderate onshore breezes. Stratus coverage may intermittently become VFR this afternoon, but should become solid MVFR around sunset time. Leaned on an optimistic clearing time for Tuesday morning, though confidence is low.

SFO Bridge Approach...Patchy stratus coverage is expected to continue into the evening. Otherwise, similar to SFO.

Monterey Bay Terminals...VFR is anticipated through the early evening hours before marine stratus re-develops. Forecast confidence is low to medium as the current satellite presentation of stratus is very disorganized. At this time, the expectation is that stratus will invade KMRY just after sunset this evening, with MVFR arriving a few hours after that at KSNS. While IFR is a possibility, the current TAF set leans on a more optimistic ceiling forecast given the amount of dry air likely just above the marine layer. Otherwise, diurnal breezes with speeds of 8-12 knots are advertised throughout the TAF cycle.

MARINE

(Tonight through next Sunday) Issued at 514 PM PDT Mon Aug 31 2026

Northwest to westerly gentle breezes will persist through the week with intermittent periods of moderate breezes. Wind driven seas are anticipated to remain slight to moderate through the week with long period southerly swell persisting thanks to tropical cyclone activity.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Tuesday for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 PM PDT this evening for Mry Bay.