085 FXUS66 KMTR 151632 AFDMTRArea Forecast Discussion National Weather Service San Francisco CA 932 AM PDT Wed Oct 15 2025
...New UPDATE, MARINE...
.KEY MESSAGES... Updated at 106 AM PDT Wed Oct 15 2025
- Warming and drying trend kicks off today and lasts through Saturday
- Long period northwesterly swell will bring an increased risk of sneaker waves and rip currents to Pacific Coast beaches by Saturday
- Unsettled weather possibly returns Sunday
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.UPDATE... Issued at 932 AM PDT Wed Oct 15 2025
Drying conditions will return to the region today. Temperatures may be cooler than previously forecast for today, as low clouds linger across much of the region. These clouds are forecast to clear out across the Central Coast this afternoon, but may not clear until this evening across the North Bay and Bay Area. Temperatures remain about 10-20 degrees F below seasonal averages with a gradual warming trend through Saturday.
RGass
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.SHORT TERM... Issued at 106 AM PDT Wed Oct 15 2025 (Today and tonight)
Isolated rain shower activity will continue to wane through the morning with dry conditions expected by daybreak or shortly there after. A warming and drying trend kicks off today as upper-level shortwave ridging nudges the mid-to-upper level low east. It certainly won`t feel like it though with widespread temperatures of 10-20 degrees below normal. Patchy frost will be possible tonight for far interior portions of Monterey and San Benito Counties. Frost or not, it is going to be cold and proper precautions should be taken to protect people, pets, and plants.
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.LONG TERM... Issued at 106 AM PDT Wed Oct 15 2025 (Thursday through Tuesday)
By tomorrow, surface high pressure will build into the Pacific Northwest which will create a northerly (drying) gradient across the state. Surface high pressure will continue to build into the Great Basin Friday into Saturday with a coastal trough developing off the coast of California. This pattern will facilitate textbook offshore flow as pressure flows from high to low and winds follow suit. Both of these patterns will be no cause for concern fire weather (or other) wise with the recent widespread wetting rainfall putting a damper, but not quite an end, to fire weather season. Global ensemble clusters are in agreement that a cut-off low will get pinched off from leftover troughing from the beginning of the forecast period with heights falling by Sunday. What that means for us is still up in the air (literally). A cut-off low is uncertain by nature due to it`s independence from the jet stream, but the big question here is what kind of flow regime are we going to be in? Heights rising? Heights falling? Split flow where it`s some combination of both? Zonal? It`s difficult to say, but either way it does not look to be impactful no matter the solution. The deterministic ECMWF and GFS both have an upper-level longwave trough moving into the region Sunday. The ECMWF has a quicker solution while the GFS has a slower, deeper solution that would be able to absorb the cut-off low back into the jet stream. As of now the forecast is dry, but there is still a significant amount of spread amongst total precipitation ensembles. For now, I would expect an increase in cloud cover and winds over the weekend. Unfortunately this uncertainty will impact the confidence in the forecast at the beginning of next week; thus, it is uncertain on if heights will rebuild or if the aforementioned trough will continue to dig.
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.AVIATION... (12Z TAFS) Issued at 436 AM PDT Wed Oct 15 2025
Departing system and lingering low level moisture has led to a mixed bag of lingering showers and MVFR cigs. That being said, conditions do continue to gradually improve and will so through the AM rush. Expect VFR this afternoon with a few fair weather CU. clearing skies tonight will also for some patchy stratus to develop. Conf is moderate overall.
Vicinity of SFO...CIGS 2500-3500 will lingering through 17-18Z based on satellite trends and latest guidance. About a 10-20% chc for a VCSH, but not high enough to include in TAF. Winds mainly light to moderate. Some SCT CU this afternoon.
SFO Bridge Approach...Similar to SFO. Could see a lower CIGS occasional cause issues with visuals through AM rush.
Monterey Bay Terminals...MVFR to VFR conditions this AM. VFR this afternoon with MVFR cigs develop tonight.
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.MARINE... (Today through Monday) Issued at 932 AM PDT Wed Oct 15 2025
Weather conditions improve today through late week as the low pressure systems departs. Light winds persist across the waters today, increasing to a fresh breeze Thursday afternoon. A longer period northwesterly swell will arrive over the weekend.
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.MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. &&
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SHORT TERM...Sarment LONG TERM....Sarment AVIATION...MM MARINE...Behringer
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NWS MTR Office Area Forecast Discussion