textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1201 AM PDT Wed Aug 19 2026

- Compressed marine layer today, increases Thursday into the weekend

- Near normal temperatures today followed by a gradual cooling into the weekend

- Elevations above about 1000 feet will have warm temperatures and RH values in the teens this morning into the afternoon

SHORT TERM

Issued at 1201 AM PDT Wed Aug 19 2026 (Today and tonight)

A slightly more shallow marine layer tonight resulted in a somewhat later onset of stratus pushing inland with less extensive coverage than what was seen last night into early Tuesday morning. Another mild overnight into early this morning should result in stratus retreating back to the coast an hour or two sooner than we generally see this time of year. Todays warmup will barely be noticeable for areas below 1000ft away from the coast, with temperatures at higher elevations across the East Bay Hills and Santa Lucias including Big Sur and the Timber fire, running 10 degrees or more above normal. MinRH values will be in the teens this afternoon across those elevated locations, fortunately light winds continue to be a mitigating factor. The weak fetch of offshore flow above the marine layer over the southern Central Coast will shift late tonight with improved RH recovery expected into early Thursday, along with an increase in the marine layer depth.

LONG TERM

Issued at 1201 AM PDT Wed Aug 19 2026 (Thursday through Tuesday)

Troughing persists through the extended forecast with gradually cooling setting in on Thursday and continuing through the weekend into next week. The persistent ridging to our east increases to near 600dm by the middle of next week, while continuing steer at least a couple of tropical waves around its perimeter well to our south. The potential tropical system still depicted beyond the official forecast period still appears to offer little impact for our area while we will continue to monitor any mid-level moisture advection.

AVIATION

(06Z TAFS) Issued at 942 PM PDT Tue Aug 18 2026

Currently a mixed bag of LIFR-VFR. Prevailing persistence forecast tonight with little change in the pattern or marine layer. As such, IFR ceilings are forecast to impact all terminals tonight. If the marine layer compresses, lower chance of it reaching LVK or SJC. VFR expected for most by tomorrow afternoon with low stratus sticking close to the coast. HAF will likely remain sub-VFR through the TAF period with a low chance for ceilings to hang on at MRY and SNS through the day. Diurnal winds will prevail.

Vicinity of SFO...Currently IFR with northwesterly flow. High confidence in VFR prevailing by tomorrow afternoon. Diurnal winds will prevail. Lower (40%) confidence in the return of an IFR ceiling tomorrow night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently LIFR with southwesterly flow at MRY and IFR with northwesterly flow at SNS. SNS is expected to further deteriorate to LIFR with LIFR-IFR conditions expected through tomorrow morning at both terminals. Low stratus will stick to the coast during the afternoon with another early return tomorrow evening. Diurnal winds will prevail.

MARINE

(Tonight through next Monday) Issued at 942 PM PDT Tue Aug 18 2026

Moderate to fresh northwesterly breezes will prevail through Saturday. Locally strong northwesterly breezes across the northern outer waters and along the coastal jet regions will bring hazardous conditions for small craft into Thursday. Rough seas in the outer waters will abate Thursday with moderate seas prevailing by Friday.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.