textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1213 PM PDT Sun Oct 4 2026

- Warm to hot conditions across the region through mid-week

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

- Elevated fire weather conditions persist in the interior through Thursday

SHORT TERM

Issued at 1213 PM PDT Sun Oct 4 2026 (This evening through Monday night)

It's hot. A persistent ridge over the western United States keeps the area much above the seasonal average (15 to 25 degrees above seasonal average away from the immediate coast). As of 11 AM today temperatures across the region ranged from the 80s into the lower 90s inland, the 70s to the lower 80s close to the Bays, and the middle 60s to the middle 70s for the Pacific coast. There are some high clouds flowing above the SF Bay Area, but they do not seem to be impacting the heat levels. High temperatures today and Monday will be rather similar in the inland valleys, ranging from the middle 90s to near 104. Closer to the Bays, today's highs will be in the middle 80s to the middle 90s while locations along the Pacific coast rise into the 70s. Across the higher elevations and some nearby valleys, especially in the East and South Bays, mild overnight lows in the upper 60s to middle 70s will limit the ability to recover overnight. For Monday, these temperatures are a little uncertain owing to potential impacts from a shallow marine layer or a marginally stronger onshore flow than the current forecast, but highs should remain in the 70s and 80s. If confidence in highs towards the higher part of that range increases, the Heat Advisory for our coastal regions may need to be extended.

Due to the hazardous heat levels, a Heat Advisory is in effect for coastal locations through 10 PM tonight, while inland and Bayshore areas remains under the Advisory through Wednesday. Widespread Moderate HeatRisk blankets the region, 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 in addition to the East Bay, South Bay, and the Carmel, Hollister, and northern Salinas Valleys see 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 1213 PM PDT Sun Oct 4 2026 (Tuesday through next Saturday)

The ridging persists for the next few days and as previously mentioned, the Heat Advisory extends to Wednesday night for the inland and Bayshore regions. Temperatures across the inland valleys remain in the middle 90s to near 105 through Wednesday. Along the Pacific, we continue to monitor how the forecast trends evolve as impacts from a shallow marine layer or stronger onshore flow than the current forecast may significantly impact the immediate coast.

A pattern change will begin Thursday as the ridge flattens and troughing develops in the northeastern Pacific and moves into southwestern Canada and the western United States. This will start a cooling trend with most locations dropping out of Moderate HeatRisk by Friday. Ensemble model cluster analysis hints at significant uncertainty for the upcoming weekend and the early part of the upcoming week regarding the strength of the trough and how long it could persist.

AVIATION

(18Z TAFS) Issued at 1029 AM PDT Sun Oct 4 2026

VFR conditions regionwide throughout much of the day with light onshore winds forecast to return by mid-afternoon. Winds begin to diminish after sunset and more so into Monday morning. The greatest potential for low ceilings and/or fog to occur Monday morning will be at coastal sites (MRY, HAF, and to a lesser extent SNS) as high cloud cover is forecast to diminish throughout the day. However, confidence is low-to-moderate for fog development in these locations.

Vicinity of SFO...VFR. Weak offshore winds currently with weak to moderate onshore flow expected by mid-afternoon. Winds ease overnight and into early Monday morning with generally high confidence of VFR conditions persisting through the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Light drainage winds currently at SNS will shift onshore by early afternoon and prevail before easing after sunset. The greatest potential for sub-IFR conditions will be at MRY early Monday morning, less confidence for SNS. Any low clouds and/or fog that does develop is likely to dissipate by 16Z Monday.

MARINE

(Today through Friday) Issued at 833 AM PDT Sun Oct 4 2026

Northwesterly breezes will remain gentle to moderate into midweek, allowing for slight to moderate wave heights to persist.

FIRE WEATHER

Issued at 405 AM PDT Sun Oct 4 2026

Hot and dry conditions will continue through Thursday, which will be accompanied with weak offshore flow. Poor to very poor overnight recovery is expected for the thermal belts, generally for elevations above 1000-1500 feet, leading to elevated fire weather conditions. The marine layer is expected to be confined to the immediate coast and around 500 feet. If working in the thermal belts, Moderate to Extreme HeatRisk is forecast this week, with temperature and HeatRisk trends improving late week. A pattern change is expected late in the week or over the weekend. Cooler weather and the potential for improved RH recovery is forecast or Friday.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 10 PM PDT this evening for CAZ006-502-505- 509-528>530.

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

PZ...None.