textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1104 PM PDT Mon Apr 6 2026

- Above normal temperatures and dry conditions through Wednesday

- Unsettled weather returns Thursday with below normal temperatures and beneficial rainfall

- Isolated to scattered thunderstorms Thursday and Friday

SHORT TERM

Issued at 1104 PM PDT Mon Apr 6 2026 (Tonight through Wednesday night)

Upper-level shortwave ridging will dominate our weather through Wednesday. This will result in above normal temperatures and dry conditions. Fortunately, a decent marine layer of about 1,500 feet is expected during this time which will keep conditions cooler at the coast and the natural air conditioning on.

LONG TERM

Issued at 1104 PM PDT Mon Apr 6 2026 (Thursday through next Monday)

A vertically stacked surface low in the Eastern Pacific Ocean near 37 N, -140 W will kickoff our pattern change. As it encroaches our marine zones on Thursday, it'll increase PWAT values to near the 90th percentile (0.79 inches for 12Z April 9th). The RRFS sounding profile can be characterized by low CAPE, conditionally unstable lapse rates, and low shear. As such, a slight (up to 15%) chance for thunderstorms is being advertised for Thursday. Thunderstorm chances increase Friday (15%-25%) as the surface low moves inland. Thunderstorm impacts include lightning, locally heavy rainfall, erratic/gusty winds, and small hail. There still remains uncertainty in the exact location and timing of the cutoff low as this feature is notoriously difficult to forecast due to their independence from the Polar Jet Stream. As such, rainfall totals on Thursday and Friday will be heavily dependent upon where rain showers/thunderstorms develop. Upper-level longwave troughing develops off the West Coast Saturday as an upstream trough digs south and connects with the cutoff low with the help of a dip in the Polar Jet Stream. As a result, widespread beneficial rainfall, below normal temperatures, and strong onshore winds are expected Saturday into Sunday with a cold frontal passage. Gusts up to 40 mph can be expected in the higher terrain and through west-east oriented gaps and passes. When all is said and done, rainfall on the order of 0.25"-0.75" inches is expected with locally higher totals of 1.00"- 1.50" inches in the coastal ranges.

AVIATION

(12Z TAFS) Issued at 448 AM PDT Tue Apr 7 2026

Maritime air and stratus clouds /MVFR-IFR/ continue to move inland supported by a predominant pressure gradient 2.6 mb SFO- SAC; a surface ridge of high pressure was located over the CA coastal and offshore waters. The marine layer depth varies from 1500 to 2000 feet. Above the marine layer, lower to mid level thermal and height ridging (above early April normal) persists. High resolution model forecasts show stratus mixing out by late morning and afternoon with areas of stratus returning tonight and Wednesday morning.

Vicinity of SFO...Stratus /MVFR/ until 18z mixing out to VFR for the afternoon and evening. West wind near 10 knots increasing to 15 to 25 knots from late morning through early to mid evening. West wind 5 to 10 knots tonight and Wednesday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus /MVFR-IFR/ until late morning then mixing out to VFR for the afternoon and early evening. Stratus redevelops tonight and Wednesday morning. Onshore winds 5 to 12 knots.

MARINE

(Today through Sunday) Issued at 426 AM PDT Tue Apr 7 2026

Surface high pressure off the California coast will result in light to moderate breezes across the coastal waters to Wednesday before diminishing. Low pressure over the eastern Pacific will then bring wet weather including a slight chance of thunderstorms mid to late week. A separate low may arrive from the northwest and bring additional wet weather this weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 9 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.