textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1212 PM PDT Sun Aug 9 2026

- Widespread moderate with areas of major HeatRisk for the interior Sunday

- Elevated to near-critical fire weather conditions in the higher terrain through Monday

- Minor coastal flooding for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay through Thursday morning

SHORT TERM

Issued at 1212 PM PDT Sun Aug 9 2026 (This evening through Monday night)

A more compressed marine layer allowed for rapid clearing of stratus to the immediate coastline late this morning. As such, have left the Heat Advisory in place for much of the interior Bay Area and Central Coast through 10 PM this evening. However, locations under the around 500-800 foot marine layer may struggle to reach their afternoon maximum forecast temperatures. This is especially so around the San Jose region, yet the southern Santa Clara Valley has the potential.

Minor coastal flooding is also expected around the time of the highest high tide (evening/overnight) for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay through Thursday morning. The decision not to include the Pacific Coast was made yesterday evening when the forecast fell below the predicted values, yet still high enough to maintain the aforementioned bays. Please see the CFW product we have out for additional details. Also, for more on the fire weather concerns through early in the week, please see the Fire Weather Section of the AFD below.

During this weekend's heat event, remember:

* Stay hydrated and drink plenty of fluids. * Wear lightweight and light-colored clothing. * Reduce time spent outdoors or stay in the shade. * Never leave people or pets unattended in vehicles. * Use sunscreen if going to the coast or the pool.

Afternoon temperatures are forecast to cool some 5-10 degrees on Monday as a weak shortwave trough develops off of the West Coast. As such, HeatRisk levels lower to minor with pockets of moderate.

LONG TERM

Issued at 1212 PM PDT Sun Aug 9 2026 (Tuesday through next Saturday)

The troughing would also support coastal drizzle and/or mist each night and morning through late week. Temperatures cool to below normal (as much as 20 deg F below by Friday) as a reinforcing upper level through develops off of the Bay Area and Central Coast. As this low pressure approaches the coastline late in the week and monsoonal moisture advects northward around the high over the Four Corners, there is the potential for high-based convection. There remains a great deal of uncertainty of whether or not there will be enough instability aloft to support thunderstorms. While this is still far out in time and low confidence, any dry lightning would be problematic from a fire weather standpoint. Be sure to check back for additional details as we move closer to midweek.

AVIATION

(18Z TAFS) Issued at 1040 AM PDT Sun Aug 9 2026

Stratus is largely receding with the exception of HAF where an eddy will keep stratus variable through the afternoon. VFR, outside of HAF, through this evening with breezy onshore winds during the afternoon/evening. Stratus returns overnight but confidence is mixed on the exact timing. HRRR guidance suggests a patchy return late tonight while HREF guidance shows a more traditional widespread early return of stratus. It will likely be a mix of both where stratus is widespread again tonight but may return later in the night. Initial clearing times look to be between 17-18Z but it could clear as early as 16Z (persistence forecast).

Vicinity of SFO...Stratus is clearing over the SF Bay with VFR conditions expected through this evening. Stratus is forecast to return around 09-10Z and persist through late Monday morning. Highest confidence in IFR CIGs tonight. Breezy onshore winds expected during the afternoon/evening today and again tomorrow.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR but some uncertainty remains as to the timing of stratus return later today. The current TAF has stratus returning between 04-06Z with IFR to LIFR ceilings expected. At the same time, an otter eddy is developing in the Monterey Bay this morning which may result in additional cloud cover pushing into MRY/SNS early this afternoon. Confidence is low that this will occur but it remains a possibility. Breezy onshore winds are expected this afternoon/evening before winds weaken overnight.

MARINE

(Today through Friday) Issued at 907 AM PDT Sun Aug 9 2026

Fresh to strong northwest winds persist with rough seas up to 12 feet today through mid week. Northern coastal waters will be hazardous for small craft with occasional near gale force gusts possible through early week. The San Francisco Bay north of the Bay Bridge into the Delta will have gusty onshore winds through late evening. Long period southerly swells at around 15 to 17 seconds continue.

FIRE WEATHER

Issued at 1206 AM PDT Sun Aug 9 2026

Near-critical fire weather conditions persist today across the interior due to very hot and dry conditions. Strong thermal belting, extended burn periods, elevated PIG, and near or record BI/ERC values are expected. Temperatures will be 10 to 15 degrees above normal with a compressed marine layer. Poor minimum daytime relative humidity as low as 10% in the afternoons with little-to- no recovery overnight is expected with nocturnal drying in the highest terrain. Even with critically dry conditions, wind is the limiting factor preventing this from being a Fire Weather Watch/Red Flag Warning event. Outside of the diurnal sea breeze that will bring breezy conditions in the afternoons and evenings through gaps and passes, onshore flow will be light. Additionally, critical conditions are not expected to meet coverage or duration requirements to warrant a product. Localized elevated fire weather conditions in the highest terrain can be expected Monday due to the combination of recent hot/dry conditions and the increase in onshore flow. Depending how the pattern and marine layer evolves, a headline may be warranted and this could last through Wednesday.

Sarment

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory until 2 AM PDT Thursday for CAZ006-506- 508-529-530.

Heat Advisory until 10 PM PDT this evening for CAZ503-504-510- 512>518.

PZ...Small Craft Advisory until 9 PM PDT this evening for SF Bay N of Bay Bridge.

Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt Reyes 0-10 nm.

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