textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 925 PM PDT Sat Sep 19 2026

- Brief cooling Sunday through Monday

- More substantial warming trend Tuesday through Thursday

SHORT TERM

Issued at 925 PM PDT Sat Sep 19 2026 (Tonight through Monday night)

Residual polar jet stream winds will merge with the subtropical jet stream at the base of a weak 500 mb low currently ~ 500 miles west of Monterey and move the low eastward across our forecast area later Sunday through Monday. Cool onshore breezes will help keep temperatures below normal. Daytime highs Sunday will be cooler than typical for Sep 20th with highs in the 60s coastside/bayside to the 70s and 80s inland. Highs Monday will be about the same as on Sunday. A few patches of late night and morning light drizzle may form in the cooled air near surface to aloft.

LONG TERM

Issued at 925 PM PDT Sat Sep 19 2026 (Tuesday through next Saturday)

500 mb low amplitude ridging will develop Tuesday into early Thursday. This will bring a warming trend here during these three days, which will help push daytime highs up to the 90s/100 inland Wed-Thu (cooler at the coastline and bays). The pattern across the North Pacific to the western CONUS is progressive, which lowers confidence a little in the timing of 500 mb ridging residence time and this may influence the duration of warm/hot weather currently forecast for mid next week. Stay tuned to the latest updates.

AVIATION

(12Z TAFS) Issued at 416 AM PDT Sun Sep 20 2026

Currently LIFR-MVFR with high clouds streaming in. IFR-MVFR ceilings will prevail through late-morning before stratus retreats to the coast. Confidence is decreasing in any fog development this morning. Moderate to high confidence in IFR-MVFR ceilings returning to all terminals tonight. Drizzle will be possible in the mornings. Diurnal winds will prevail.

Vicinity of SFO...Currently MVFR with westerly flow. High confidence in a ceiling on the cusp of IFR/MVFR prevailing through late- morning. High (80%) confidence in an MVFR ceiling returning tonight. Diurnal winds will prevail.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently IFR with westerly flow at MRY and IFR with southwesterly flow at SNS. IFR will prevail through the morning with stratus retreating to the coast during the afternoon. The close proximity may keep MRY sub-VFR through the TAF period with an early return slated tonight. Diurnal winds will prevail.

MARINE

(Today through Friday) Issued at 416 AM PDT Sun Sep 20 2026

Fresh to strong northerly breezes will create hazardous conditions for small craft across most of the coastal waters through Monday morning. Moderate to fresh northerly breezes will prevail Tuesday through Thursday with locally strong breezes across the northern outer waters. Slight to moderate seas will prevail through Monday, building to become moderate to rough Tuesday through Thursday.

FIRE WEATHER

Issued at 416 AM PDT Sun Sep 20 2026

Near to slightly below normal temperatures, diurnal winds, a deep marine layer, and a chance for drizzle are on tap for Sunday and Monday. Warming and drying trend kicks off Tuesday with temperatures up to 15 degrees above normal by Thursday. Areas of moderate HeatRisk are expected as a result Wednesday and Thursday. The marine layer will compress below 1,000 feet during this warm-up with nocturnal drying expected above it. Diurnal winds will prevail; however, they will be weaker than the preceding days.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 9 AM PDT this morning for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.