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

UPDATE

Issued at 758 AM PDT Tue May 12 2026

Satellite imagery shows extensive stratus coverage across the valleys with high clouds aloft, with the Bodega Bay profiler showing an marine layer around 1500-2000 ft deep this morning. Stratus should gradually pare back to the coastal regions through the day with some inland development expected this evening. Gusty onshore winds this afternoon and evening will contribute to the potential for elevated fire weather threat in the farthest interior regions of Monterey and San Benito Counties, particularly the areas adjacent to the Central Valley where daytime relative humidities are low and overnight recoveries are poor. Although the threat is not widespread enough for fire weather products, any well-aligned grass fires that start may take hold and spread quickly. People in these interior regions should take care to properly dispose of cigarettes and matches and avoid using equipment that creates sparks.

DialH

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

The stratus intrusion onshore has brought IFR-LIFR ceilings to most terminals which should scatter out by late morning Tuesday. The lower cloud ceilings are impacting the visibility at a few airports, though are expected to improve by 17Z. Light winds will increase to moderate strength by the afternoon with some terminals experiencing gusts up to 20-25kts. The marine layer is expected to move back onshore by Tuesday evening, though it won't be as expansive.

Vicinity of SFO...Moderate onshore winds will persist through the TAF period with gusts reaching up to 25-27 kts Tuesday afternoon. The moderate winds combined with high-level clouds should help mix out the stratus layer and shift back to VFR conditions by 18Z. The stratus deck is expected to return overnight (02-03Z) but should remain MVFR through Wednesday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...LIFR ceilings are causing misty conditions which is impacting the visibility across the terminals this morning. Conditions are expected to improve by 16-18Z with VFR conditions forecast by 19Z. Light, variable winds are expected to become moderate and onshore by the afternoon. Another night of stratus is also anticipated to return by Wednesday evening.

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 9 AM to 3 PM PDT Wednesday for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 3 PM this afternoon to 3 PM PDT Wednesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory from 3 AM to 3 PM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm.