textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1026 PM PDT Mon May 18 2026

- Diurnally driven winds, with onshore winds during the afternoon and early evening.

- Above normal temperatures continue through midweek with seasonal temperatures returning late week

UPDATE

Issued at 914 AM PDT Tue May 19 2026

Clear skies across the region this morning with much lighter winds compared to this time yesterday. Temperatures across the lower elevations are running up to 10 degrees cooler than they were yesterday morning. Oppositely, temperatures across the higher elevations are running warmer than they were yesterday morning. Highs today will be in the 80s across the interior and 60s to 70s along the coast. Higher end forecasts suggest some potential for high temperatures to reach the low 90s across interior hot spots (North Bay valleys, East Bay hills, southern Santa Clara Valley).

SHORT TERM

Issued at 1026 PM PDT Mon May 18 2026 (Tonight through Tuesday)

The forecast appears to be on track, with broad upper level troughing holding over much of the western U.S. while high pressure builds over the eastern Pacific. The good news, is that our breezy offshore winds have eased substantially leaving us with fairly calm weather in return. Tonight, skies will remain clear and temperatures will generally fall into the 50s for the valleys, perhaps upper 40s for some coastal sites and the southern Salinas Valley. At higher elevations, a thermal belt will exist as temperatures fall into the mid 50s to low 60s and may still have some northerly winds. For those in the valleys, winds will generally be light and variable.

Tomorrow, another warm day will be on tap. The question will be, how do the temperatures pan out? Offshore flow won't be as prevalent, which means there could be less of a downsloping / warming of the air affect. But, that upper level high slowly creeps towards us and the marine layer is essentially negligible. Opted to blend a bit of the observations from Monday to the NBM giving us a similar forecast, to what occurred yesterday. The interior Bay Area valleys should make it into the 80s, perhaps near 90 degrees, while coastal communities experience a tighter gradient of highs in the 60s to low 70s. The San Francisco Peninsula should be similar, with the Pacific side having temps range from the mid 60s to low 70s, while the Bay side ranges from the upper 70s to mid 80s. And finally the Central Coast, interior locations rise into the mid 70s to mid 80s, while coastal communities vary from the mid 60s to the low 80s.

LONG TERM

Issued at 1026 PM PDT Mon May 18 2026 (Tuesday night through next Monday)

No major changes to the extended forecast. Upper level troughing looks to keep hold over the western US through at least Wednesday, with that Pacific high slowly peeking into northern CA. This should bring a return of onshore flow to the region and eventually the marine layer. Warm weather looks to linger through at least Wednesday, with Thursday potentially seeing a slight change in temperatures if the marine layer develops. Guidance for Thursday caps it at 500ft at best, with the marine layer getting to 1000ft by Friday. The marine layer appears to better establish itself Friday night into Saturday, likely getting to around 1000ft again. Will need to keep an eye on this as it will affect how temperatures pan

AVIATION

(18Z TAFS) Issued at 1021 AM PDT Tue May 19 2026

VFR will prevail the remainder of today and tonight with a chance of MVFR/IFR cigs developing around sunrise Wednesday. Light and variable winds this morning become light but steady onshore this afternoon and evening.

Vicinity of SFO...VFR is expected through today and tonight with a slight chance of MVFR cigs developing around sunrise Wednesday with confidence too low for mentioning in the TAF attm.

SFO Bridge Approach...Similar as SFO.

Monterey Bay Terminals...VFR will prevail today and tonight with a chance of MVFR/IFR cigs developing around sunrise Wednesday morning. Expect light and variable to light onshore winds through the TAF period.

MARINE

(Today through Sunday) Issued at 914 AM PDT Tue May 19 2026

Fresh northerly breezes will continue over the northern outer zones through tomorrow with hazardous conditions through Thursday morning. Wave heights increase again on Thursday with increasing northwest swell that eases for the end of the weak into the weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.