textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1200 AM PDT Fri May 22 2026

- Diurnally driven onshore winds during the afternoon and early evening

- Warm and dry weather today leads to elevated fire weather concerns for the interior Bay Area and Central Coast

- 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 Fri May 22 2026 (Today and tonight)

The stratus deck has completely covered the coast and is flowing through the Petaluma Gap into the Sonoma County valleys, through the Golden Gate into the Berkeley area, and across the Monterey Bay region and up the Salinas Valley. The Bodega Bay profiler reports a marine layer around 1000-1500 ft thick, which would allow stratus to fill into the North Bay Valleys, the East Bay west of the Berkeley- San Leandro Hills, the Santa Clara Valley, and perhaps impacting the area around Hollister over the course of the night before stratus retreats to the immediate coast through the post-sunrise hours this morning.

An upper level ridge over the northern Pacific that extends into the Pacific Northwest is continuing to flatten under the influence of a trough centered over Alaska, allowing a gradual cooling trend to begin today. NBM model output continues to run a little warm, so I have tamped down today's high temperature forecasts. They're still a shining example of the impact of the Bay Area and Central Coast's famous microclimates, with high temperatures ranging from the middle 80s to the lower 90s in the inland valleys of the Bay Area and Central Coast, to the upper 50s to lower 60s along the Pacific Coast. In between the two are the North Bay valleys, where highs range from the middle 70s to lower 80s, the Bayshore regions where highs range in the 70s, tending warmer the closer you get to the southern edge of San Francisco Bay, and downtown San Francisco itself where temperatures top out around the middle 60s. Breezy onshore winds will develop during the afternoon and evening hours, with gusts up to 15 to 25 mph through favored gaps and passes.

Continuing hot and dry conditions across the interior regions will contribute to another day of elevated fire weather concerns. For those living or visiting those hot and dry regions, keep the following in mind:

* Properly dispose of cigarettes and matches * Do not use a lawn mower on weeds or dry grass * Avoid using equipment that creates sparks * Make sure campfires are completely put out * Make sure no vehicle parts drag on the ground, including towing chains * Obey burn bans & only burn with a permit

LONG TERM

Issued at 1200 AM PDT Fri May 22 2026 (Saturday through Thursday)

The aforementioned cooling trend continues through the early part of next week, and by Saturday, temperatures should be near the seasonal average with highs in the middle 70s to the middle 80s inland. Early next week, a cold front associated with a deep upper low is expected to make its way through the region, and the ensemble model runs are starting to agree on a period of cooler temperatures and stronger onshore flow Monday through Wednesday. The slight chance for light rain or drizzle continues across favored coastal regions as the front passes through, as is the concurrence of the models that any rainfall that develops will be very light with few hundredths of an inch being a reasonable higher end amount for any region.

Towards the later part of the week, the ensemble model runs begin to diverge as the evolution of the upper level low and incoming ridging becomes uncertain. Most runs lean towards a warming trend for that period, which is reflected in the current forecast, with a significant minority (around 30-40% of the runs) suggesting that some form of trough lingers through the period.

AVIATION

(06Z TAFS) Issued at 938 PM PDT Thu May 21 2026

Currently a mixed bag of LIFR-VFR at the terminals. Moderate to high confidence on IFR-LIFR conditions returning to all the terminals tonight with the exception of the interior terminals of LVK and SJC. Diurnal winds will prevail.

Vicinity of SFO...Currently VFR with northwesterly flow. Stratus is currently being held off just to the northwest of the terminal. Moderate confidence on this reaching the terminal, likely around 09Z. Diurnal winds will prevail.

SFO Bridge Approach...Low clouds coming in through the Golden Gate Gap will continue to spread south along the East Bay Shoreline tonight with the San Mateo Bridge Approach likely to be impacted through late morning.

Monterey Bay Terminals...Currently IFR with southwesterly flow at MRY and IFR with northwesterly flow at SNS. High confidence on conditions deteriorating to LIFR with fog possible. VFR is expected by late morning with IFR stratus sticking close to the coast during the day. Another early return of stratus is expected tomorrow night.

MARINE

(Tonight through next Wednesday) Issued at 938 PM PDT Thu May 21 2026

Hazardous conditions for small craft continue tonight for the northern outer waters due to strong northerly breezes and rough seas. Moderate northwesterly breezes will back to become southwesterly tomorrow and prevail through the weekend. Rough waters are expected across the northern outer waters Friday with widespread moderate seas prevailing Saturday through Monday.

MTR WATCHES/WARNINGS/ADVISORIES

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