textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1 AM PDT Mon May 11 2026

- Warming and drying trend will continue through Monday

- Moderate risk for heat-related illnesses for sensitive populations across the interior East Bay on Monday

- Gradual cooling trend and unsettled weather midweek through late week

SHORT TERM

Issued at 1226 AM PDT Mon May 11 2026 (Today and tonight)

Upper level ridge still remains locked over CA, but that will change after today. Let's first take a look at the marine layer situation. Similar to yesterday we still have a marine layer. You can definitely tell there's a ridge overhead due to compressed nature and discontinuous coverage of the stratus. Satellite fog product does show decent coverage along most of the coast, but inland coverage is lacking and less than 24 hours ago. Expect some additional expansion through sunrise. Will need to rely on the building May sun angle to help erode the stratus by this afternoon. Not much surface forcing to get rid of it. Regardless, today will be the peak of our little warm spell. 850 mb temps are still on track to be 20-22C, which under ideal conditions would yield max temps in the mid 90s. However, we still have some marine layer influence. The last three days NBM guidance was just too warm across the interior and think today will be the same. Did shave a few degrees from the NBM for today. Max Temps will be in the 60s to 70s coast and bays and 80s to mid 90s far interior. The slight downward trend on temps has now kept Moderate HeatRisk confined mainly to the East Bay interior valleys.

By tonight the ridge shifts eastward and gets replaced by an approaching upstream trough. As such, 500 mb heights begin to fall and the airmass cools. The marine layer will develop again and with the exiting ridge coverage will be more and deeper.

LONG TERM

Issued at 1226 AM PDT Mon May 11 2026 (Tuesday through Sunday)

Tuesday will be a transition day as the ridge is to the east and a cut-off low develop off the NorCal coast. Deeper marine layer to start the day and cooling airmass will lead to cooler temperatures with no HeatRisk concerns. Temps will still be still above normal, but trending toward seasonal averages.

There was more uncertainty regarding the longwave pattern midweek, but the latest cluster run and ensemble guidance has given a more clear picture. The cut-off low from Tuesday night deepens and then sweeps through NorCal - taking the more northern track. So wait does that mean? Will still have some light rain and/or drizzle in the forecast for the N Bay/ SF/ SF Peninsula late Tuesday night through early Wednesday. Not expecting much in the way of accum. Higher confidence this passing low will bring temps back to seasonal averages.

Zonal flow then develops for the rest of the work week into next weekend with dry conditions and moderating temps.

AVIATION

(06Z TAFS) Issued at 950 PM PDT Sun May 10 2026

No major changes to the forecast with this TAF package. Tonight's observations include Mainly VFR conditions with the exception being along the San Francisco Peninsula and Monterey coastlines where sites are reporting MVFR to IFR cigs. These will likely hold and even build for the overnight hours bringing MVFR to IFR ceilings. The marine layer is expected to be around 1000ft tonight which means the onset of stratus in the valleys will be delayed or non-existent. Most sites have hints of cigs, with them lifting by mid to late morning. VFR conditions are expected for the majority of the region by Monday afternoon. The marine layer looks to return again tomorrow evening, opted to hint or fully bring it in for terminals near the coast. Medium to high confidence in the forecast.

Vicinity of SFO...Westerly winds are winding down and will fall to around 10kt or less after 6Z. The challenge outside of winds is the stratus. Satellite imagery and webcams show stratus building around the San Francisco Peninsula and slowly filtering into the western portion of KSFO's range ring. With the marine layer expected to be around 1000ft again, we should see the return of stratus tonight. Kept the pessimism in the TAFs with IFR cigs based on the last few nights, but time will tell if go that low or stay in the MVFR category. Stratus looks to dissipate mid to late morning, with breezy westerlies of 10-15kt returning Monday afternoon. The marine layer looks to return Monday night into Tuesday morning, which was brought into the latest TAF. Medium confidence in the forecast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...A small band of stratus remains around the Monterey Peninsula, which has been brought IFR cigs to KMRY. Expect this to build back in this evening bringing MVFR to IFR cigs to the terminals. Stratus should begin to erode by mid to late morning, though a few clouds could linger around KMRY for the afternoon. Stratus and low cigs look to return Monday evening.

MARINE

(Tonight through next Saturday) Issued at 845 PM PDT Sun May 10 2026

Moderate seas and a fresh to strong northwest breeze with isolated near gale force gusts continuing through tonight. Winds ease late tonight across the inner waters then across the outer waters tomorrow becoming a moderate to fresh northwest breeze. Seas subside in response, but remain moderate with 4 to 5 foot seas by mid week.Locally gusty conditions are likely across the San Pablo and San Francisco Bays where terrain promotes wind funneling. Winds increase and seas build again late Wednesday into Thursday.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT early this morning for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 PM PDT this afternoon for Pt Arena to Pt Reyes 10-60 NM.

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