textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1155 PM PDT Sun Aug 2 2026

- Moderate HeatRisk in the interior through Tuesday, becoming patchy midweek

- Near critical fire weather threat across the interior North and East Bays, and the Diablo and Santa Lucia ranges through Monday with elevated fire weather threat through the week

- Widespread Moderate HeatRisk looks to return for the end of the work week.

SHORT TERM

Issued at 1255 PM PDT Mon Aug 3 2026 (This evening through Tuesday night)

Nearterm:The southerly surge continues to inch its way northward along the coast and finally made it past Pt Reyes. The surge has really taken a bit out of temperatures along the immediate coast this afternoon. 24 hr trends show many locations along the coastline are running cooler than Sunday, which isn't surprising with nearby clouds. On the flip side, head inland and away from the surge influence and temps are soaring into the 90s and lower 100s. As such, Heat Adv remains in effect through this evening for Interior North Mts and Interior East/South Bays.

Tonight through Tuesday night: The surge will become less of a surge and more just onshore with more stratus. Moderate marine layer stratus coverage for inland areas tonight. This stratus will bring some relief and better RH, but above the shall layer will remain mild and dry.

Interesting set up for Tuesday as the upper level pattern shows a slight rebound of the ridge, but lower surface levels keep the southerly/onshore flow. Pretty hard to bet again stratus and cooler SST along the coast. As such, temperatures for Tuesday will be within a few degrees of Monday, but on the cooler side. Just enough to knock down HeatRisk values to Moderate with little to no Major.

Tuesday night will see even more stratus coverage with a slight deepening.

One final concern for the short term will be smoke/haze. Ample fire activity across OR/WA will push some smoke over the coastal waters. Longer range RRFS actually brings some smoke/haze to the coastal waters late Tuesday into Wednesday.

LONG TERM

Issued at 1255 PM PDT Mon Aug 3 2026 (Wednesday through next Sunday)

Rinse and repeat for the long term, but in the other direction with a gradual warming and drying trend.

Upper level high pressure that briefly flattened will rebuild over the West Coast beginning late Wednesday lasting through at least Friday. While there is a slight reprieve in temps mid-week inland heat and increasing HeatRisk return Thursday and more so Friday. In fact, some of the guidance suggest an airmass approaching 30C at 850mb. 30C is a pretty toasty airmass, which would easily yield max temps over 100 across the interior. Would also expect mild overnight lows in the hills. If this trend continues we may need another Heat Advisory.

AVIATION

(00Z TAFS) Issued at 420 PM PDT Mon Aug 3 2026

VFR conditions will prevail through much of the overnight except for the Monterey Bay terminals, where stratus is expected to begin to move in after sunset. The marine layer continues to struggle but may begin to rebound slightly tonight, along with a more impactful KSFO-KWMC pressure gradient. Outside of the Monterey Bay terminals, the MVFR/IFR ceilings are expected to return closer to the pre-dawn hours and clear by late morning.

Vicinity of SFO...VFR through much of the overnight with MVFR/IFR ceilings expected to return in the pre-dawn hours and lift by late morning. Breezy onshore flow will develop by late afternoon and persist through the evening hours.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR until after sunset when IFR/LIFR ceilings are expected to spread over the peninsula into the Salinas Valley. VFR conditions should return by early afternoon, a little sooner at KSNS with steady, occasionally breezy onshore flow Tuesday afternoon.

MARINE

(Tonight through next Saturday) Issued at 420 PM PDT Mon Aug 3 2026

Northwest moderate to fresh breezes prevail into the evening with occasional strong gusts across the far northern outer waters. By tomorrow, winds become light to gentle (5-10 kt) with some degree of variability in the wind direction, generally from the southwest. Widespread moderate northwest winds around 15 kt settle in towards the end of the week. West-northwest seas continue to subside to moderate and remain around 4-8 feet through the work week.

FIRE WEATHER

Issued at 420 PM PDT Mon Aug 3 2026

Near critical fire weather conditions continue through this evening, with elevated fire weather conditions persisting through the middle of the week, and potentially a return of near critical conditions later in the week. Temperatures remain around 10 to 15 degrees above normal across the interior (except for Wednesday, with near normal temperatures) through early next week with highs in the upper 80s to 90s. No major changes to the forecasted dry conditions. Daytime humidity retention remains poor across the interior (20-30%) with humidity values dropping into the 10s across the interior Central Coast, East Bay Hills/Valleys, and the higher elevations. Portions of the interior Central Coast may see daytime humidity values drop into the single digits Tuesday, then again towards the end of the week into the weekend. Overnight RH recovery remains poor at locations above 2,000 feet with values between 25 to 40% expected with some favored locations struggling to reach even 25%. This will be particularly true across the Mayacamas, highest peaks of the East Bay Hills, the Diablo Range, the Santa Cruz Mountains, the Santa Lucia and Gabilan Ranges. Nocturnal drying (rapid decrease in RH through the pre- dawn hours) may also transpire which will increase the burn period or time in which fire behavior may remain active. Energy Release Component (ERC) values are projected to climb above the the percentile across the interior Central Coast, Mid Coast to Mendocino (North Bay), and Diablo- Santa Cruz (Diablo Mountains and Santa Cruz Mountains) zones by the middle of the week. Diurnally breezy onshore winds are expected along the coast, mountain gaps and passes, and along the ridgelines each afternoon/evening. With near critically dry conditions and above normal temperatures expected, individuals across these areas are advised to avoid activities that may spark a fire. Fire crews are urged to exercise extra caution when executing any prescribed burns, especially where fuels, topography, and weather align.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 10 PM PDT this evening for CAZ504-510- 513>515.

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