textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1219 PM PDT Tue Jul 21 2026

- Heat Advisory in effect for interior Central Coast and Bay Area through 9 PM PDT

- Breezy onshore winds return for the second half of the week

- Temperatures will hover around normal through the week

SHORT TERM

Issued at 1219 PM PDT Tue Jul 21 2026 (This evening through Wednesday night)

Have went ahead and issued a Heat Advisory through 9 PM this evening for interior areas of the Bay Area and Central Coast. Temperatures overnight and into this morning didn't cool off as much as originally expected, thanks to the mid/upper level cloud cover across the region. That combined with temperatures forecast to reach the 90s (potentially exceeding 100 deg F in the warmest interior spots) across the interior made for widespread Moderate HeatRisk. Today is forecast to be the hottest of the week!

For tonight, expecting an increase in low level stratus to return to the coast and expand inland into the coastal adjacent valleys. There is a greater than 50% probability of this occuring as mid- to-high level clouds begin to shift to the east as remnant moisture from Elida gets absorbed in the mean flow aloft. Cannot rule out coastal drizzle tonight, depending on if the shallow marine layer is able to redevelop. It will feel muggy once again tonight as humidity remains elevated.

Tomorrow will feature a significant cool down thanks to an increase in onshore winds and stronger marine influences. Temperatures across the interior will warm into the mid 70s to mid 80s with the warmest interior spots reaching into the lower 90s across the Central Coast. Meanwhile, cooler conditions will prevail near the coast with day time highs in the mid 60s to mid 70s.

LONG TERM

Issued at 1219 PM PDT Tue Jul 21 2026 (Thursday through next Monday)

Not much change to the forecast beyond the short term. Still expecting troughing off of the Pacific Northwest coast as high pressure remains over the interior West through late week. This will generally keep conditions near seasonal averages with night/morning low clouds working their way inland and then retreating to the coast by the afternoon. As the high pressure appears to shift more toward the Four Corners region, we may see the marine layer compress over the weekend with a slight inland warming trend.

AVIATION

(18Z TAFS) Issued at 1200 PM PDT Tue Jul 21 2026

VFR conditions will prevail with mid-level clouds quickly lifting to the north leaving behind mostly clear skies. The marine layer is expected to reform tonight around 1,000 feet which would bring ceilings on the cusp of IFR/MVFR to bayshore and coastal terminals with lower confidence farther inland. This may be generous given the over performance of guidance and models currently, it'll all depend on if mid-level clouds can clear overnight. Diurnal winds will prevail.

Vicinity of SFO...VFR conditions with west to northwesterly flow will prevail. Moderate to high confidence on VFR prevailing through much of the TAF period. MVFR cigs possible by early morning Wednesday.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions with moderate northwesterly winds will prevail. Moderate confidence on ceilings on the cusp of IFR/MVFR returning tonight.

MARINE

(Tonight through next Sunday) Issued at 1200 PM PDT Tue Jul 21 2026

Light northwesterly breezes are expected today, backing to become southerly tomorrow. Hazardous conditions for small craft may return as early as Thursday as northwesterly breezes return and increase to become moderate to fresh through Saturday. Moderate southwesterly swell from tropical cyclone activity in the Eastern Pacific will bring mixed seas and potentially hazardous conditions through the weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...Heat Advisory until 9 PM PDT this evening for CAZ502-504-506-508- 510-512>518.

PZ...None.