textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1236 PM PDT Mon Oct 5 2026

- Hazardous heat conditions inland persist through Thursday, never leave children or pets in unattended vehicles!

- Elevated fire weather conditions persist in the interior through Thursday

- Cooler temperatures possible late this week

SHORT TERM

Issued at 1236 PM PDT Mon Oct 5 2026 (This evening through Tuesday night)

Stratus clouds lurk at the immediate coast, associated with a shallow marine layer around 500-1000 feet thick, but the rest of the region remains hot through the next couple of days as ridging persists across the western United States, ridging which is helping compress the marine layer and preventing any substantial overnight relief from reaching the higher elevations. To our northeast, high level clouds and convective remnants, associated with a puff of moisture riding an embedded low in the larger scale ridging, linger over the northern Sierra Nevada range and into the northern sections of the Great Basin. This time yesterday, that puff of moisture was streaming over the Bay Area, resulting in streaming high clouds that contributed to some cooler (relatively speaking) conditions than the expectation. Today the skies remain clear, and it's possible for today's high temperatures to overperform yesterday's, especially across the North Bay. High temperatures today and Tuesday range from the middle 90s to near 106 across the inland valleys, the middle 80s to the lower 90s near the Bays, and the upper 60s to the lower 70s along the Pacific coast. Mild overnight lows in the higher elevations, ranging from the upper 60s to the middle 70s, along with weak onshore flow will limit overnight recoveries.

A Heat Advisory remains in effect for the interior regions, excluding the coastal strip and the northern Salinas Valley, as widespread Moderate HeatRisk blankets the interior, corresponding to a moderate risk of heat-related illnesses for sensitive populations, including children, the elderly, pregnant women, people with chronic illnesses, and people who work or live outdoors without access to adequate cooling or hydration. In addition, many of the higher elevations are seeing Major HeatRisk, corresponding to a high risk for heat-related illnesses for anyone without hydration or cooling. Follow these tips to avoid heat exhaustion and heatstroke:

* Stay hydrated and drink plenty of fluids. * Wear lightweight, 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.

LONG TERM

Issued at 1236 PM PDT Mon Oct 5 2026 (Wednesday through next Sunday)

Ridging persists for the next few days and the Heat Advisory has been extended to Thursday night for the inland and Bayshore regions. Temperatures across the inland valleys remain in the middle 90s to near 105 into Thursday; despite a couple of degrees of cooling on Thursday, hazardous heat lingers across the region and widespread Moderate HeatRisk persists in the inland regions. Patches of HeatRisk linger into Friday across the interior, and the Heat Advisory may need to be extended if confidence in heat-related impacts increases.

Towards the latter part of the seven day outlook, uncertainty in the forecast increases as the ridge starts to break down and a trough begins to develop along the West Coast. Ensemble model cluster analysis suggests a split between solutions that bring something akin to an inside slider to the Great Basin for the upcoming weekend and those that keep the ridging in play. The inside slider solution slightly dominates the cluster space at this time, but we will wait for the model trend to become clearer before committing to a particular solution.

AVIATION

(18Z TAFS) Issued at 1047 AM PDT Mon Oct 5 2026

A shallow marine layer (around 500 feet in depth) has returned allowing for coastal stratus and fog to return to the coastal sites. As surface temperatures warm, expecting mostly VFR conditions to persist through the early evening before a return of stratus and/or fog returns to coastal sites late this evening and into Tuesday morning. The greatest potential for sub-IFR will be at HAF, MRY, and SNS with the rest of the region remaining VFR throughout the TAF period. Onshore winds will increase today and be slightly stronger than previous days before easing after sunset and more so into Tuesday morning. Any low ceilings and/or fog are likely to dissipate between 16Z-17Z Tuesday.

Vicinity of SFO...VFR. Onshore winds will increase by late morning and persist into early evening before diminishing. West to northwest winds will be strongest this afternoon through mid- evening with winds forecast to be up to 16kt. While there is a low probability (generally 20-25%) of sub-MVFR from 12Z-17Z Tuesday, have these out of the forecast at this time.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Onshore winds will increase this afternoon before diminishing after sunset. Sub-IFR conditions are forecast to return to the region late this evening and persist into Tuesday morning with generally moderate to high confidence of occurrence. Low ceiling and fog will begin to dissipate between 16Z- 17Z Tuesday with afternoon heating.

MARINE

(Today through Saturday) Issued at 930 AM PDT Mon Oct 5 2026

An extensive low stratus and fog layer is steadily advancing eastward across the coastal waters and will reach much of the coastline throughout the morning and into the afternoon. A gentle to moderate breeze and slight to moderate wave heights persist into midweek. Winds increase and wave heights build, seas becoming rough across the outer waters, Friday into the weekend.

FIRE WEATHER

Issued at 306 AM PDT Mon Oct 5 2026

Strong ridging aloft will lead to hot and dry conditions through Thursday with elevated fire weather conditions across the higher elevations. Poor to very poor overnight humidity recoveries will continue across the thermal belts with pushes of offshore flow each morning. Hazardous heat will continue through Thursday with major to extreme risks of heat-related illnesses across most mountain ranges. A pattern change later this week will bring cooler conditions to the region.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 10 PM PDT Thursday for CAZ503-504-506-508- 510-512>518.

PZ...None.