textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1209 PM PDT Tue Aug 11 2026

- Low confidence for elevated showers and thunderstorms Wednesday afternoon through Thursday morning across the Central Coast

- Cooling trend continuing into Thursday, bringing temperatures below seasonal averages with gradual warming Friday into the weekend

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

SHORT TERM

Issued at 1209 PM PDT Tue Aug 11 2026 (This evening through Thursday morning)

Stratus clouds linger along the immediate coast through the day, before coming into the inland valleys overnight into Wednesday morning. Smoke from the Timber Fire south of Big Sur continues to be transported northwards into the Monterey Bay region due to southwesterly transport winds, and this is expected to continue through the next couple of days. For air quality forecasts, refer to products issued by the Monterey Bay Air Resources District within the Central Coast, and the Bay Area Air Quality Management District within the San Francisco Bay Area.

The weather pattern is dominated by a developing upper level trough that will continue a cooling and moistening trend through the next couple of days. Today's high temperatures range from the 80s and lower 90s in the inland valleys, up to the middle 90s in the warmest interior spots, the 70s and lower 80s along the Bays, and the lower to middle 60s along the Pacific Coast. Lows tonight into Wednesday morning range from the 50s and lower 60s within the lower elevations, up to the middle 60s to lower 70s above the marine layer influence at around 2000 feet. Overnight drizzle is possible along the coast and within favored upslope foothill areas through the Petaluma Gap and within the East Bay.

For Wednesday, attention turns to an upper level low that is currently meandering around 300 miles southwest of Point Conception, where space- and ground-based observations have pointed to some lightning occuring within a high-based thunderstorm cell. Through the next couple of days, that cell will start to move along a moisture gradient, which could locally enhance the lapse rates, into the Central Coast, with around a 10-15% probability of high-based showers and thunderstorm activity across Monterey and San Benito Counties between Wednesday afternoon and the early part of Thursday morning. Primary threats are gusty outflow winds and the potential for dry lightning and its attendant fire weather implications; see the FIRE WEATHER section for more details. Main question right now is if the cell will hold together as it approaches the coast. Water vapor imagery is showing a layer of drier air within the cell's path, which could disrupt the system as it approaches California. Elsewhere, the general cooling trend continues as highs reach the upper 70s to middle 80s inland, the upper 60s to the middle 70s near the Bays and the lower to middle 60s along the Pacific coast.

As a final note, minor coastal flooding is possible across the low lying bayshore areas of the San Francisco, San Pablo, and Monterey Bays at the highest high tide through Wednesday night/Thursday morning. At the San Francisco tidal gauge, high tide is expected to be 1.6 ft above normal (7.44 ft MLLW) at 10:57 PM Tuesday 8/11 and 1.4 ft above normal (7.24 ft MLLW) at 11:49 PM Wednesday 8/12. High tides may result in flooding along coastal trails, cut off access to some low-lying coastal areas and beaches, and bring water and waves farther up the beach than typical. If travel is required, allow extra time as some roads may be closed. Do not drive, bike, or walk around barricades or through water of unknown depth.

LONG TERM

Issued at 1209 PM PDT Tue Aug 11 2026 (Thursday afternoon through next Monday)

The cooling trend continues through Thursday with highs in the inland valleys dropping into the 70s, or around 10 to 20 degrees below the seasonal averages, possibly as high as the middle 80s in the warmest spots, and highs into the 60s close to the Bays. Beginning on Friday, the trough begins to flatten out, allowing for gradual warming to occur, although temperatures will remain below seasonal averages given that the troughing pattern never really goes away, it just merges with another trough coming in from the eastern Pacific and lurks just offshore for the weekend before migrating back over the West Coast for the early part of next week, when highs will be in the middle 70s to lower 80s inland and the middle 60s to lower 70s near the Bays.

AVIATION

(00Z TAFS) Issued at 428 PM PDT Tue Aug 11 2026

VFR prevails across the area with the marine layer lingering along the coastline. The gradual increase in depth of the marine layer is underway and is expected to reach ~2000ft later tonight through the middle of the week at least. However, active offshore eddys continue to complicate the progression inland and impacts over the Bay Area. Despite being surrounded overnight and early this morning KSFO still didn't register a ceiling. So even if not being reported directly at the terminal be prepared for low ceilings in vicinity of terminals near the coast.

Vicinity of SFO...VFR is expected to prevail at KSFO through the forecast period, however expect MVFR/IFR ceilings on approach after sunset through Wednesday morning. KOAK is expected to develop MVFR/IFR ceilings around/soon after midnight, earlier than previous couple nights as the marine layer depth continues to gradually increase.

SFO Bridge Approach...MVFR/IFR ceilings likely on approach even if not reported at KSFO.

Monterey Bay Terminals...Once again, more typical diurnal pattern of MVFR/IFR ceiling development for this time of year than points north. MVFR/IFR ceilings expected prior to sunset and continuing through the middle to late morning Wednesday, returning around the same time Wednesday early evening.

MARINE

(Tonight through next Sunday) Issued at 428 PM PDT Tue Aug 11 2026

Fresh to strong northwest winds persist into Thursday with occasional near gale force gusts possible tonight across the northern outer waters. Wind driven rough seas continue to build up to 12 feet across areas with strong breezes. A long period southerly swell gradually increases to 17 to 19 seconds by the end of the week. Visibility impacts due to haze and smoke is possible across the coastal waters due to an active fire on the Big Sur coastline.

FIRE WEATHER

Issued at 1209 PM PDT Tue Aug 11 2026

Near-critical fire weather conditions are forecast for Monterey and San Benito counties as a low pressure system currently around 300 miles southeast of Point Conception moves onshore Wednesday afternoon through Thursday early morning. Observations from space- and ground-based instruments suggest that a high-based convective cell within that low pressure system is producing lightning. If the cell holds together, that could bring a chance of lightning-induced fire starts to the region, especially within higher elevation areas that have continued to see poor to very poor overnight humidity recoveries. Examples include the Santa Lucia range, adjacent areas of Los Padres National Forest, and the Gabilan range within interior Monterey and San Benito counties. Given the high-based nature of the thunderstorms, there may be little to no rainfall associated with the cells, raising the prospects for dry lightning. In addition, gusty and erratic outflow winds could promote fire growth for ongoing fires and new starts near a thunderstorm complex. The main source of uncertainty lies in the behavior of the system as it moves closer to shore, potentially into a dry slot in the upper levels, that could impact how the cell develops as it moves onshore. This is currently a low confidence, high impact scenario, especially given ongoing fire activity with the Timber Fire and intense tourist activity within the Monterey Bay region. If confidence in thunderstorm impacts increases through the night, a Red Flag Warning may need to be issued. Beyond the passage of the cells, fire weather conditions should improve as a deepening ridge causes the marine layer to deepen and overnight humidity recoveries to increase to relative humidity values of 40% and above within the higher elevations.

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MTR WATCHES/WARNINGS/ADVISORIES

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

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