textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1216 AM PDT Tue May 12 2026

- Gradual cooling trend develops today through midweek

- Warming and drying trend midweek and beyond

SHORT TERM

Issued at 1216 AM PDT Tue May 12 2026 (Today and tonight)

The pattern shift discussed on yesterday's AFD is upon us. A quick snapshot of the longwave pattern over the West shows a ridge sneaking off to the east and settling over the Desert SW and knocking on CA is an upstream upper trough and associated cut-off low. Onshore flow plus lower 500 mb heights equals a deep marine layer presences this morning. Satellite fog product shows a decent marine layer with way more inland intrusion than 24 hours ago. Marine layer depth will vary from 1000-1500 feet this morning. Light mist or drizzle will be possible along the immediate coastline through this morning.

Deeper marine layer and onshore flow will lead to a later clearing time of inland stratus for Tuesday. The coast on the other hand may not see much in the way of clearing today. Noticeable cooldown for Max Temps today bringing readings closer to seasonal averages. Max Temps 60s to 70s coast/bays and 70s to lower 90s interior.

If we follow the trend is your friend logic: the upstream upper low has been trending more north and continues to do so. As such, the chance for widespread drizzle and/or light rain has now been removed from the forecast late Tuesday night into Wednesday. That being said, still expecting another push of marine stratus overnight.

LONG TERM

Issued at 1216 AM PDT Tue May 12 2026 (Wednesday through Monday)

The upper low will sweep through Oregon during the day on Wednesday. While the forecast has trended drier temperatures will still be on the cool side. Wednesday will be coolest day of the forecast. Additionally, expect some breezy onshore winds through out the day. Winds will be strongest along the coast and inland gaps/passes.

Quiet weather returns for the second half of the work week and into the weekend with zonal flow, warming temps, night/morning clouds.

AVIATION

(06Z TAFS) Issued at 949 PM PDT Mon May 11 2026

Stratus has brought MVFR to IFR cigs to the coast and some interior North Bay valleys and the northern Salinas Valley. Models trend with the marine layer at 1000 feet, but it might get closer to 1200 feet tonight. This will bring yet another night of low clouds and potentially visibility. Trended the forecast to account for the inland push in the North Bay, while East and South Bay terminals hold similar timing to the previous TAFs. Stratus should burn off by mid to late morning, breezy onshore flow is expected tomorrow afternoon and evening. Medium to high confidence in the forecast.

Vicinity of SFO...Breezy westerly winds should begin to decrease within the next hour or so becoming less than 10kt for the overnight hours. The stratus looms just west of the terminal, with VFR conditions prevailing. The onset of stratus should occur later tonight, but there are also some models showing the stratus arriving closers to 12Z, with low clouds mixing out by 17-20Z. Breezy westerlies return tomorrow afternoon, with gusts up to 21kt by 21Z and 30kt closer to 30Z. Breezy winds look to last into the evening with gusts to 20-25kt potentially lasting through 6Z. Medium confidence in the forecast.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...The actual Bay is socked in with stratus which is making a good inland push. KMRY has already succumbed to the stratus, with cigs falling to LIFR. KSNS is following suit, with another night of low cigs and vis for them and other terminals. Most guidance stratus mixing out by mid to late morning, with the exception being at KMRY. There is uncertainty if we'll be able to fully clear, or if we'll get a few pockets of sunshine between 18- 23Z. Medium to high confidence in the forecast.

MARINE

(Tonight through next Sunday) Issued at 949 PM PDT Mon May 11 2026

Occasional strong gusts continue through tonight across the far northern outer waters. Otherwise, a moderate to fresh northwest breeze will continue over the waters through midweek. Seas subside but remain moderate with 4 to 6 foot seas through midweek. Winds increase and seas build starting mid-week with gale force winds and wave heights in excess of 10 feet likely starting Friday and continuing through the weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pt Arena to Pt Reyes 0-10 nm-SF Bay N of Bay Bridge.