688 FXUS66 KMTR 081236 AFDMTRArea Forecast Discussion National Weather Service San Francisco CA 536 AM PDT Wed Oct 8 2025
...New AVIATION, MARINE...
.KEY MESSAGES... Updated at 152 AM PDT Wed Oct 8 2025
- Cooler and cloudier weather today
- Drizzle tonight through Thursday morning
- Light rain chances increase Friday through Saturday morning for the North Bay, Bay Area and East Bay
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.SHORT TERM... Issued at 152 AM PDT Wed Oct 8 2025 (Today and tonight)
A weak upper level low that has lingered off the central coast the previous few days has begun evolving into an open wave overnight and will eventually be absorbed by a deepening trough to our north later this afternoon. The pattern change in motion this morning will result in inland temperatures today that will be 5-15 degrees cooler than yesterday and up to 5 degrees cooler along the coast. A weak surface trough out ahead of the first of numerous upper level trough axis` passing through our area the rest of the week, will bring areas of drizzle tonight through Thursday morning.
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.LONG TERM... Issued at 152 AM PDT Wed Oct 8 2025 (Thursday through Tuesday)
The persistent troughing pattern through the extended forecast period will keep temperatures around or below normal well into next week. Rain chances continue primarily for the North Bay Friday into early Saturday, with thunderstorm chances around 5% or less Friday afternoon. Consensus is good wrt the overall pattern through the weekend. Extended deterministic guidance has poor consensus on the potential for widespread wetting rainfall for the beginning of next week. ECMWF/Canadian models have strong signal for rain, while the GFS has little to no rain in our area for that same time frame. The NBM is clearly leaning on the ECMWF/Canadian solutions, which seems reasonable attm. The difference being the GFS deepens an upper level disturbance farther inland, while the ECMWF/Canadian indicate a more plausible deepening of the system just offshore and push it south along the coast, giving it more time to pick up moisture along the way.
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.AVIATION... (12Z TAFS) Issued at 536 AM PDT Wed Oct 8 2025
Nearly widespread MVFR and IFR CIGs are expected through much of the morning. Cloud cover lifts and scatters into the late morning and early afternoon. Leading to mostly VFR conditions across the region, with the exception of STS, which will fail to clear. Expect moderate to breezy winds through the afternoon and into the evening before winds weaken and cloud cover builds in the North Bay and along the immediate coast with chances for drizzle.
Vicinity of SFO...VFR through the TAF period. Expect passing low clouds around the SF Bay through the morning that will thin out into the afternoon as moderate southwest winds build. These winds look to weaken and turn more southerly into the night as scattered mid-level clouds build.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...MVFR CIGs linger into the afternoon before eroding as winds increase. Cloud cover struggles to return into the evening while winds reduce into the night.
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.MARINE... (Today through Monday) Issued at 536 AM PDT Wed Oct 8 2025
Expect mostly light to moderate winds into the late week. Drizzle and pockets of fog affect the waters late Wednesday through much of Thursday. Light showers arrive to the northern waters Thursday night and last into late Friday. Winds across the waters build over the weekend with additional and prolonged rain chances arriving into the next work week.
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.MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. &&
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SHORT TERM...JM LONG TERM....JM AVIATION...Murdock MARINE...Murdock
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