Area Forecast Discussion

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

(00Z TAFS) Issued at 447 PM PDT Tue Jul 21 2026

VFR is expected to prevail for all terminals until around midnight when we begin to feel the effects of a pattern change as the influence of the remnants of Elida shift north. Marine stratus is expected to arrive a little later than normal diurnal patterns, and clearing Wednesday morning will shift later into the morning hours to early afternoon.

Vicinity of SFO...Onshore flow overnight will become breezy Wednesday afternoon with MVFR/IFR ceilings expected after midnight tonight and persisting into the early afternoon, with light drizzle possible in the early morning hours.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR until later tonight, with MVFR/IFR ceilings returning, possibly before midnight. Expect IFR ceilings by sunrise with a chance of drizzle as well with a later clearing time into early afternoon Wednesday, then VFR through the remainder of the forecast period.

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...Small Craft Advisory from 9 PM Wednesday to 9 PM PDT Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.