textproduct: San Francisco Bay Area

KEY MESSAGES

Updated at 1238 PM PDT Fri Sep 25 2026

- Cooler conditions through the weekend

- Warmer temperatures next week

SHORT TERM

Issued at 1154 PM PDT Fri Sep 25 2026 (Tonight through Sunday)

Cooler air continues to move in on northwest winds; the ACV-SFO pressure gradient is 3.4 mb and SFO-SAC is 1.9 mb. Cooler air is combining with nocturnal radiative cooling and upsloping winds forming patchy low clouds and mist. Radiative cooling will also help result in patchy valley fog forming overnight and Saturday morning.

On average our Sep weather pattern has been influenced by large scale troughing, with many areas away from the coastline benefiting from below Sep normals for the month to date. If you're enjoying the weather, it's a nice weekend shaping up with Saturday daytime highs in the 60s/70 at the coast, mostly 70s inland except in the 80s across the southern interior of Monterey and San Benito counties. Also for Sunday daytime highs will be below late Sep normals with highs mainly in the 60s and 70s, quite nice, it could be warmer/hotter this time of year.

LONG TERM

Issued at 1154 PM PDT Fri Sep 25 2026 (Sunday night through next Friday)

Cool temperatures carryover into Monday, then warming returns Tuesday through late week with increasing 500 mb ridging. Dry weather is forecast during this timeframe. Daytime highs Tuesday through late week will warm back to the 80s to lower 90s inland while it'll be cooler nearer the coast with highs generally in the upper 60s and 70s.

AVIATION

(12Z TAFS) Issued at 420 AM PDT Sat Sep 26 2026

Pockets of MVFR have developed this morning across the Napa River Valley and bayshore portions of the East Bay (including APC and OAK) thanks to clear skies and sufficient low level moisture. The depth of this moisture is shallow per our presently ascending weather balloon from OAK and should translate to clearing roughly between the 15-17Z timeframe. MVFR cigs are more probable to linger at KHAF through at least 21Z, though there's some indication that VFR may not return today. A storm system will approach the region toward 12Z Sunday, resulting in VFR ceilings around FL120. Moisture above the marine layer (roughly around 1,000-1,500 ft) to around 12,000 ft is minimal. However, noteworthy lift will translate to moistening of this layer with a potential for weak convection capable of pockets of turbulence and virga below FL120.

Vicinity of SFO...MVFR cigs are anticipated (and will at times be intermittent) through 17Z with moderate confidence that VFR will return by 18Z today. Winds today are anticipated to be a bit more subdued through the San Bruno Gap. A compact upper low will approach early Sunday morning during the 24-30 hour portion of the SFO TAF. Onshore flow is expected to encourage more of a marine MVFR cigs push, with another cig, albeit VFR, around FL120. Virga/turbulence below cloud base cannot be ruled out.

SFO Bridge Approach...Clouds are probable to impact the approach from PAO and SQL, though it appears that areas near SJC will remain SKC. Clearing is expected by the 17Z-18Z time frame.

Monterey Bay Terminals...Remnant turbulence in the wake of Friday's cold front has disrupted fog development and the current TAF set is slightly more optimistic, especially at KSNS. Occasional IFR stratus is still anticipated to persist through at least the 15Z at MRY. The approach of an upper storm system should encourage stronger onshore flow and result in MVFR ceilings. While guidance does suggest a 02Z-03Z window, the marine layer is likely to struggle to re-develop after a couple of days of dry continental flow and it's probable that this initial surge will be intermittent. The current TAF set estimates that the best window for more persistent cigs to be closer to 04Z. MVFR will prevail through sunrise Sunday. While the potential for IFR is too low to include at this juncture, it's non-zero and we'll monitor trends in guidance for potential inclusion in subsequent TAF issuances.

MARINE

(Today through Thursday) Issued at 420 AM PDT Sat Sep 26 2026

Fresh to strong northerly breezes are forecast to continue through the weekend. This will equate to hazardous boating conditions, especially for waters beyond 10 nautical miles from the shoreline. Near gale forced wind gusts will be ushered in behind a departing upper storm system early next week. The strongest gusts are expected across northern outer waters.

FIRE WEATHER

Issued at 420 AM PDT Sat Sep 26 2026

Our diffuse cold front continues to slowly move southward through Southern California. In its wake, some areas have benefited from the cooler and slightly more "moist" conditions this morning. The exception, however, is across the higher terrain of the Santa Cruz Mountains as well as the Santa Lucia and Diablo Ranges where RH recovery remains poor (20-40%). Afternoon humidity will remain under 40%, largely for areas away from the coast. A push of onshore flow is expected later this evening into Sunday morning resulting in the marine layer deepening to around 2,000 feet ahead of an upper trough. This moisture push should diminish the areal coverage of poor RH recovery Sunday and Monday morning. A few sprinkles cannot be ruled out along the highest peaks associated with this upper low Sunday AM. Dry and modest offshore breezes will be a possibility Tuesday and into Wednesday, with the potential for wind gusts above 35 mph being greatest across the higher terrain of the North Bay in the wake of this upper low. Farther south across the Central Coast, the primary impact from this low will be a return to widespread poor RH recovery with some locales across the Santa Lucia Range struggling to see max RH above 30% Wednesday morning.

MTR WATCHES/WARNINGS/ADVISORIES

CA...None. PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt to Pt Pinos 10-60 NM.