textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 218 PM PDT Tue Sep 8 2026

- Warming and drying trend will bring widespread moderate to major HeatRisk through Thursday

- Cooler temperatures, closer to normal, Friday into the weekend

SHORT TERM

Issued at 218 PM PDT Tue Sep 8 2026 (This evening through Wednesday night)

Temperature's early this afternoon are running 5-10 degrees warmer than they were at this time 24hrs for most locations across our area, including the coastal communities. A weak fetch of offshore flow aloft with a weaker unorganized signal at the surface is still holding back the marine layer influence from penetrating farther inland. Decided to start the Heat Advisory this afternoon instead of Wednesday morning due to warmer than normal temperatures overnight beginning tonight along with the warmer than normal daytime temperatures. With a shallow, unorganized marine layer persisting through tonight and Wednesday, decided to increase temperatures slightly for Wednesday to lineup more with current trends. Along with a lack of a well organized marine layer, PWATs are expected to gradually increase between now and Wednesday afternoon. As noted in the previous forecast, we'll approach values that come close to daily climatological records for this time of year. Although, some high cloud cover is expected, we're not expecting enough to significantly impact daytime max temperatures. That added moisture will make for higher RH values with the warmer temperatures, making for a muggy day and more heat related health impacts.

Please remember these tips to help mitigate impacts from heat exposure:

-Suspend unnecessary outdoor activities during the extreme heat, but if you must be outdoors, take frequent breaks in the shade or AC and drink cool water. -Know the signs and symptoms of Heat Exhaustion vs. Heat Stroke! Heat Stroke can be deadly if not treated immediately by a medical professional. Call 911 if you suspect someone is suffering from Heat Stroke. -Wear a life jacket, swim near a lifeguard, and check conditions before entering the water if going to a river or ocean to cool off. Rivers and the ocean are extremely cold, and Cold Water Shock can turn into paralysis and drowning if you are not careful. -Use a cool and damp towel on your body if you do not have AC and are feeling hot. Or, take a cool shower or bath. -Do not leave kids or pets in a parked car. -Ensure pets and livestock have access to shade and water.

LONG TERM

Issued at 218 PM PDT Tue Sep 8 2026 (Thursday through next Monday)

The pattern change from high heat to cooler will highlight the challenge going in to the long term forecast. Confidence is high that the pattern change will occur and we'll see a notable cool down. However, there may be some room in the forecast for the end of the weekend into the beginning of next week for temperatures to be higher than currently forecast depending on how progressive an upper level system across the Great Basin moves inland and suppresses the top of the ridge currently producing the warm temperatures.

AVIATION

(00Z TAFS) Issued at 431 PM PDT Tue Sep 8 2026

VFR across the board. STronger onshore flow will bring some breezy conditions this evening and again tomorrow afternoon/evening.

Vicinity of SFO...VFR with a few high clouds. Gusty onshore flow tomorrow with gusts up to 20 kt.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR...watching some low clouds/fog develop in Monterey Bay and moving toward the peninsula. Low conf on impacts to MRY,but a 20-30 pct chc of low clouds impacting SNS overnight. Conf is not high enough to include them for SNS at this time, but will monitor for 06z package.

MARINE

(Tonight through next Sunday) Issued at 431 PM PDT Tue Sep 8 2026

Gentle to moderate northwesterly breezes will prevail through Wednesday, increasing to become fresh to strong Thursday afternoon into the weekend. Slight to moderate seas will prevail, building to become rough in the outer waters Friday into Saturday.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 10 PM PDT Thursday for CAZ006-502>506- 508>510-512>518-528>530.

Coastal Flood Advisory from 8 PM this evening to 1 AM PDT Thursday for CAZ006-506-508-529-530.

PZ...None.