textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1253 PM PDT Fri Aug 28 2026

- Slight chance of rain showers through this afternoon with thunderstorm chances focused on the Central Coast, tapering off by this evening

- Cooling trend continues into early next week

SHORT TERM

Issued at 1253 PM PDT Fri Aug 28 2026 (This evening through Saturday night)

Temperatures are struggling to warm to their forecasted maximum values this afternoon. This is as abundant mid-to-high level cloud cover from remnant moisture from former Tropical Storm Iselle moves over the region. However, we are seeing via satellite that breaks in this cloud cover are appearing off of the Central Coast. This may result in enough heating to destabilize conditions across this region. As such, we are keeping the Red Flag Warning in effect through 3 PM this afternoon given the dry lightning potential.

The mid-to-upper level moisture is forecast to shift eastward into the Sierra Nevada as the trough off of the Pacific Northwest coast deepens. Thus, rain showers and the potential for thunderstorms greatly diminishes after sunset. However, the aforementioned trough will result in a deepening of the marine layer tonight and into the upcoming weekend. Therefore, an increased probability of stratus near the coast and into the adjacent valleys overnight tonight.

Slightly warmer temperatures are expected on Saturday as low clouds that do develop overnight retreat back to the coastline by tomorrow afternoon and give way to mostly sunny skies across the interior.

LONG TERM

Issued at 1253 PM PDT Fri Aug 28 2026 (Sunday through next Thursday)

A reinforcing trough deepens off of the Pacific Northwest coast by Monday, allowing afternoon temperatures to be some 5 to 15 degrees below seasonal averages. Beyond Monday and Tuesday, the latest guidance indicates troughing off of the West Coast will be stronger than previous anticipated. Therefore, less likely to see tropical moisture from the Eastern Pacific to advect northward. However, confidence remains low at this time. Be sure to keep up to date with the latest forecast information from a trusted and reliable source.

AVIATION

(18Z TAFS) Issued at 1123 AM PDT Fri Aug 28 2026

VFR across all terminals, except for HAF where it will remain IFR until the early afternoon. Gentle to moderate onshore winds increase through the day and ease overnight. High level clouds associated with a moisture plume persist and gradually decrease this evening. Drizzle/light rain is being measured across the region which is expected to continue into the early afternoon as well.

As the moisture remnants continue on their eastward track out of our region, the marine layer will begin to build back to its usual pattern. There is currently low confidence on how widespread and organized it will be tonight as the stratus feed looks patchy on satellite to our northwest. Rather than locking in IFR to MVFR ceilings, the TAF hints at the possibility with SCT decks. High confidence for coastal sites to develop IFR ceilings later this TAF period, though the exact timing is uncertain.

Vicinity of SFO...Moderate northwest winds persist through the afternoon with some light rain nearby the terminals. Onshore winds ease through the evening with low confidence for MVFR ceilings to develop around midnight.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with gentle northwest breezes through the day. The potential for light rain near the airports persists this afternoon and gradually diminishes by sunset. Overnight, winds become more west to southwest, but remain light. Medium confidence for IFR ceilings to develop with an arrival around midnight.

MARINE

(Today through Wednesday) Issued at 957 AM PDT Fri Aug 28 2026

Fresh to strong northwest breezes persist through the weekend and diminish to moderate by the beginning of the week. A long period southerly swell peaks on Saturday around 17 seconds and gradually subsides by the end of the weekend. Moderate wind driven seas persist into next week.

FIRE WEATHER

Issued at 1253 PM PDT Fri Aug 28 2026

A Red Flag Warning remains in effect through 3 PM for dry lightning potential across the Santa Cruz Mountains and Central Coast. Refer to the Short Term section for more details.

RGass

MTR WATCHES/WARNINGS/ADVISORIES

CA...Red Flag Warning until 3 PM PDT this afternoon for CAZ512-516- 517-528>530.

PZ...Small Craft Advisory from 9 AM Saturday to 3 AM PDT Sunday for Mry Bay.

Small Craft Advisory until 9 AM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 0-10 nm.