textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1211 AM PDT Fri Aug 7 2026

- Warming trend through the weekend will result in moderate to major HeatRisk for the interior

- Near-critical fire weather conditions in the higher terrain through Sunday

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

SHORT TERM

Issued at 1211 AM PDT Fri Aug 7 2026 (Friday through Sunday)

Upper-level ridging across the Four Corners will expand westward Friday. Areas of moderate HeatRisk across the interior on Friday will expand to become widespread on Saturday and Sunday with areas of major HeatRisk. Saturday and Sunday will be the hottest days of the week with temperatures 10-15 degrees above normal. Subsidence aloft will compress the 1,000 foot marine layer, keeping relief confined to the immediate coast. Near-critical fire weather conditions persist through the weekend across the interior due to very hot and dry conditions. Minor coastal flooding is expected during the highest high tide (evening/overnight) for bayshore locations along the San Francisco Bay, San Pablo Bay, and Monterey Bay Friday evening through Thursday morning. The Pacific Coast may need to be added Sunday through Tuesday, it will depend on how the positive anomaly performs leading up to it.

LONG TERM

Issued at 1211 AM PDT Fri Aug 7 2026 (Monday through Thursday)

Global ensemble clusters are in agreement that upper-level shortwave troughing will develop Monday off the West Coast between subtropical high pressure across the Eastern Pacific Ocean and the Four Corners high. This will result in temperatures moderating to near normal and the return of a marine layer around 1,000 feet. The surface pressure gradient will support northerly winds across the waters that will be hazardous to small craft.

AVIATION

(06Z TAFS) Issued at 1000 PM PDT Thu Aug 6 2026

MVFR-IFR stratus is beginning to expand as it flows into the Petaluma Gap and starts edging into the Golden Gate. Stratus continues to expand across the coastal valleys through the night with low to moderate confidence that impacts extend into the interior East Bay. That may depend on exactly how deep the marine layer is. So far stratus has been developing later than the earlier forecast suggested and the TAFs have been updated to reflect later development times. Stratus is expected to mix out back to the immediate coastline Friday morning with the breezy onshore winds expected to resume in the afternoon. Some stratus expansion is possible Friday evening, but most coverage develops after the end of the 24-hour TAF period.

The SJC ASOS will be offline within a window from 07-13Z due to maintenance at the station; the TAF is marked AMD NOT SKED as a result.

Vicinity of SFO... Low-end MVFR stratus comes into the terminal area within the next couple of hours, with lower confidence on timing as the high resolution models start with the terminal on the edge of the stratus deck. Stratus will gradually mix out through Friday morning followed by breezy and possibly gusty northwest winds in the afternoon and evening hours. Low to moderate confidence of stratus over the terminal Friday night with high resolution models trending towards pulling the stratus deck to the north.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Low confidence in the timing of the stratus development at the terminals as observed stratus coverage is much lower than model output. Nevertheless high confidence that IFR stratus will build over the terminals through the night. Stratus will retreat to the coast late Friday morning with gentle northwest winds developing in the afternoon hours, diminishing in the evening as the stratus returns.

MARINE

(Tonight through next Wednesday) Issued at 1000 PM PDT Thu Aug 6 2026

Northwest gentle winds gradually increase to a fresh to strong breeze, particularly across the outer northern waters on Saturday through the middle of the week. Moderate northwest seas also build to rough by Sunday morning continuing into the early part of next week. Winds and seas remain elevated through the middle of next week. A long period southerly swell of 15 to 17 seconds will impact the coastal waters beginning Saturday morning.

FIRE WEATHER

Issued at 1211 AM PDT Fri Aug 7 2026

Near-critical fire weather conditions persist through the weekend 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.

Sarment

MTR WATCHES/WARNINGS/ADVISORIES

CA...Coastal Flood Advisory from 5 PM this afternoon to 2 AM PDT Thursday for CAZ006-506-508-529-530.

Heat Advisory from 10 AM Saturday to 10 PM PDT Sunday for CAZ503- 504-510-512>515-517-518.

PZ...None.