textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1200 AM PDT Sat May 23 2026

- Diurnally driven onshore winds during the afternoon and early evening through the early part of next week

- Gradual cooling trend begins today with seasonal temperatures for the upcoming weekend and cooler temperatures early next week

SHORT TERM

Issued at 1200 AM PDT Sat May 23 2026 (Today and tonight)

Extensive stratus has developed along the coast and has flowed into the North Bay valleys, the northern part of the East Bay, the Monterey Bay region, and the Salinas Valley. Readings from the Bodega Bay profiler reveal a marine layer depth of around 2000 feet, which would allow for extensive inland coverage of marine layer stratus this morning and would limit the clearing of stratus through the afternoon hours. The upper level pattern is also promoting zonal flow across the state, reinforcing the cooler and milder conditions. Thus, today's highs are a little cooler than yesterday's as the inland valleys reach the 70s and the lower 80s, while areas near the bays see highs in the middle 60s to lower 70s and the Pacific coast hovers in the upper 50s. Breezy onshore winds will develop during the afternoon and evening hours with gusts up to 20 mph through favored gaps and passes.

LONG TERM

Issued at 1200 AM PDT Sat May 23 2026 (Sunday through Friday)

A slight cooling may be noticeable in the inland valleys on Sunday with high temperatures up to 5 degrees cooler, but otherwise conditions will be similar to today with extensive morning stratus and breezy onshore winds in the afternoon and evening hours. The cooling trend continues through the early part of next week with a cold front associated with a deep upper level low expected to sweep through the region sometime on Tuesday, with temperatures in the 70s across the interior valleys, the middle to upper 60s near San Francisco bay and Santa Cruz, and the upper 50s to lower 60s near the Pacific coast and the southern Monterey Bay region. Breezy winds will develop across the region with strong gusts through the favored gaps and passes. Although there is a very slight chance (around 10% probability) of light showers or drizzle popping up in the coastal regions, widespread wetting rains (rain totals at least a tenth of an inch) are not expected.

Gradual warming is expected once the cold front passes on Wednesday, with lingering northerly winds sparking some early concern for elevated fire weather risks in the interior, although it's a little too early to pin down exact details at this point. I'm not one hundred percent sold on warming on the scale that the NBM model output depicts, but it does appear that temperatures in the 80s are at least possible for the inland valleys. Beyond the 7-day outlook, the forecast becomes more uncertain as ensemble members differ on how quickly that upper level low fills in and how the pattern evolves when it does. The CPC outlook leans towards temperatures warmer than the seasonal average (highs around 65 degrees for downtown San Francisco) and precipitations totals near the seasonal average (rain totals around one or two hundredths of an inch of rain per day for downtown San Francisco) for the last couple days of May into the first week of June.

AVIATION

(12Z TAFS) Issued at 451 AM PDT Sat May 23 2026

The marine layer looks to be around 1500 feet this morning, socking in the North Bay, Central Coast Valleys, and really only eluding the South Bay and interior East Bay terminals. So far observations have mostly been holding MVFR cigs around OVC015, though reports showed brief IFR cigs. Current thinking is that most sites will be MVFR through the period, with the potential for IFR creeping up around sunrise. Stratus erodes mid to late morning, and looks to make a return later this evening and into the overnight hours.

SFO Bridge Approach... The donut hole has partially filled this morning, with KSFO finally reporting BKN MVFR cigs. The HREF has kind of picked up the best on this, with it potentially filling all the way in over the next few hours. Whether or not that occurs, models do agree with stratus clearing by mid to late morning with perhaps a few clouds lingering into the afternoon. Mainly west- southwest to to southwest winds are expected, with winds up to 12- 15kt expected this afternoon. The marine layer looks to return tonight, which should bring another round of MVFR cigs. Confidence is low to medium for the timing of the stratus later tonight. Confidence is moderate to high for this morning's stratus.

Similar to SFO.

Monterey Bay Terminals...Stratus blankets the Bay this morning, with KSNS and KMRY reporting MVFR cigs so far. Prior forecasts had the cigs dropping to IFR by now; however, IFR cigs overall have been hard to find. If we get IFR cigs, perhaps it'll briefly be around sunrise and last for a couple of hours. Stratus should erode by mid to late morning, with VFR conditions expected for the afternoon. Another cloudy night should be on tap, likely filtering in between 2- 6Z based on the models. Trended towards what has happened the past few days given the marine layer looks to have a similar depth.

MARINE

(Today through Thursday) Issued at 242 AM PDT Sat May 23 2026

Moderate to strong northerly breezes will gradually decrease this morning over the northern outer waters allowing rough seas to gradually subside as well. Conditions remain hazardous for small crafts in the aforementioned area through 9AM Saturday morning. Elsewhere, west to southwesterly winds will remain light to gentle with moderate wave heights. Seas abate to moderate heights by midday Saturday and then hold through early Tuesday morning. An incoming trough is set to approach our waters late Monday night, bringing strong northwesterly winds and building rough seas.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 9 AM PDT this morning for Pt Arena to Pt Reyes 10-60 NM.