textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1147 PM PDT Wed Aug 19 2026

- Gradual cooling trend today into the beginning of the weekend

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

SHORT TERM

Issued at 1147 PM PDT Wed Aug 19 2026 (Today and tonight)

We've been in the middle of a subtle back and forth between troughing over the EPAC and ridging over the desert southwest the past week or so. The net result has been only small changes in our day-to-day ambient weather conditions. However, the influence of troughing nudging back to the east toward our coastline today, will result in the beginning of gradual cooling, that will continue into the weekend. Improved lower boundary layer onshore flow will help bring temperatures around 5-10 degrees below normal away from the coast, while still remaining above normal in southern Monterey County. The depth of the marine layer influence will increase as well today helping to further support cooler temperatures. The more mild overnights we've been seeing will moderate closer to normal too, leading to stratus pushing farther inland after sunset into early Friday morning.

LONG TERM

Issued at 1147 PM PDT Wed Aug 19 2026 (Friday through Wednesday)

The gradual cooling trend into the beginning of the weekend levels off by Sunday into the beginning of next week with only minor, likely unnoticeable changes through the remainder of the extended forecast. The strong dome of high pressure over the desert southwest shows hints of shifting back to the west by the end of next week, which would bring warmer temperatures, however there is still no signal for a significant pattern change. Tropical wave activity is still expected to steer well south and west of our area with little to no impacts on our forecast attm.

AVIATION

(12Z TAFS) Issued at 430 AM PDT Thu Aug 20 2026

Mix of VFR to LIFR conditions this morning as the marine layer starts to compress. LIFR-IFR conditions will improve by late morning with VFR conditions this afternoon and evening. Moderate confidence on timing of stratus return tonight with IFR-LIFR CIGs likely. Low confidence that stratus will reach LVK tonight, most likely a tempo will be needed for stratus again after 12Z tomorrow. Breezy onshore winds expected this afternoon with the SFO-WMC gradient peaking around +8 mb.

Vicinity of SFO...IFR CIGs have been eddying in and out of SFO over the last few hours with eddy activity expected to continue. Patchy IFR ceilings will continue impacting SFO through approx. 16Z but as late as 18Z. Breezy onshore winds return this afternoon and evening with gusts peaking around 25 knots. Moderate confidence in timing of stratus return tonight with IFR ceilings expected.

SFO Bridge Approach...An eddy has developed within the SF Bay region that is pulling clouds away from the SFO terminal but leaving some on the Bridge Approach path. Ceilings are most likely IFR to MVFR and will clear by late morning. Otherwise, similar to SFO.

Monterey Bay Terminals...LIFR-IFR ceilings continuing through late this morning with VFR conditions briefly returning this afternoon and evening. Stratus returns during the early evening hours with ceilings on the IFR-LIFR border. Ceilings will lower overnight with worsening visibilities towards the end of the TAF period.

MARINE

(Today through Tuesday) Issued at 430 AM PDT Thu Aug 20 2026

A moderate to fresh northwesterly breeze prevails through Friday. Hazardous conditions for small craft due to occasional strong northwest gusts continue across the outer waters and coastal jet regions into Friday. Moderate seas continue across the outer waters with wave heights increasing to between 7 to 8 feet before decreasing Friday into the weekend.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Friday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 3 PM PDT Friday for Pt Pinos to Pt Piedras Blancas 0-10 nm.