textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1219 AM PDT Wed Jul 22 2026

- Breezy onshore winds return for the second half of the week

- Temperatures will hover around normal through the week

SHORT TERM

Issued at 148 AM PDT Wed Jul 22 2026 (Today and tonight)

Low clouds and the leading edge of cooler air on southwesterly winds with the eastern side of the northward moving remnant low (once part of tropical storm Elida) rapidly moved to and filled in along the coast Tuesday afternoon and evening. The remnant low is still enveloped by a tropical air mass, but it also has had time to draw in cooler air into the circulation from the northwest. This is the air that'll cool our temperatures today, but it'll also feel muggy and damp today. There may even be a few patches of light drizzle/light rain in the newly arriving moisture rich and cooler air mass combination.

Since about 8 pm to 10 pm Tuesday, an increase in surface dewpoint temperatures (higher water vapor) has spread across about the entire forecast area. Dewpoint temperatures in the 50s and 60s are now widespread.

An area of increasing larger scale subsidence and a clearing sky coincided with maximum diurnal surface heating on Tuesday, boosting daytime highs well above normal including breaking several record high temperatures in our forecast area for July 21st. However, other long term stations such as Santa Rosa, San Francisco, Napa, Kentfield, San Jose and Livermore with a period of record back including July 1917 were in the middle of a several day heat wave this time in 1917; none of these stations reached record highs on Tuesday.

Daytime highs today will be noticeably cooler even far inland: 60s/70s coastside to the 70s/80 bayside and 80s/90s far inland. Lows in the 50s to lower 60s tonight.

LONG TERM

Issued at 148 AM PDT Wed Jul 22 2026 (Thursday through Tuesday)

More typically drier (gradually less humid) summer weather develops Thursday onward to the weekend, along with onshore breezes, night and morning low clouds and fog and possibly patchy drizzle. High pressure may compress the marine layer over the weekend bringing a slight warming trend to inland areas.

The latest ECMWF and GFS show dry conditions in the 700-500 mb layer, mostly if not entirely dominated by mid-latitude winds over our forecast area for the next 10 days. Any daytime heating potential instability will be capped by thermal and height ridging at least out through 84 hours according to the 00z NAM model.

AVIATION

(12Z TAFS) Issued at 409 AM PDT Wed Jul 22 2026

The marine layer quickly reorganized last night, and is now around 1800 feet deep according to the 12Z weather balloon. The stratus pattern is a little non-standard, however. Winds are out of the south to southwest, meaning the coastal stratus is interacting with the mountains differently than the standard NW regime. Winds will gradually shift back to west and NW through the day as the clouds retreat back to the coast.

Vicinity of SFO...The southerly winds are a big help to SFO this morning. Stratus is banked up along the taller Santa Cruz mountains. With a marine layer depth of 1,800 feet, the clouds are unable to cross the ridge and spill over to the terminal. There is a separate patch of stratus forming over the East Bay hills that may expand to reach the terminal, but it's not totally clear if the terminal will develop a ceiling or not. The best window is between 12-18Z. If the winds change back to NW, the probability of a ceiling goes way up.

SFO Bridge Approach...More likely to stay clear than SFO this morning.

Monterey Bay Terminals...MRY and SNS are both socked in this morning. The cloud base has actually started to rise thanks to moderate winds. If those winds can hold on, it's unlikely IFR conditions will return this morning. MRY will probably only get a few hours of clearing this afternoon.

MARINE

(Today through Monday) Issued at 409 AM PDT Wed Jul 22 2026

A moderate southerly wind will gradually shift to NW through Wednesday afternoon. Winds will increase to a fresh NW breeze Thursday-Friday, with similar conditions continuing into next week. Significant wave heights will remain moderate this week before long period southerly swell from Hurricane Fausto reaches the coastal waters this weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 9 AM to 9 PM PDT Thursday for Mry Bay.

Small Craft Advisory from 3 PM Thursday to 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 9 AM Thursday to 3 AM PDT Friday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory from 9 PM this evening to 3 AM PDT Friday for Pt Pinos to Pt Piedras Blancas 0-10 nm.