FXUS66 KMTR 050929 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 129 AM PST Mon Jan 5 2026 ...New SHORT TERM, LONG TERM, BEACHES... .KEY MESSAGES... Updated at 1203 AM PST Mon Jan 5 2026 - Rain returns today with urban and minor river flooding possible, particularly in the North Bay - One last day with coastal flooding from king tides and storm surge in the San Francisco Bay - Hazardous Beach Conditions Thursday - Friday - Drier weather moves in Tuesday and remains through next week - Cold morning temperatures starting Thursday && .SHORT TERM... Issued at 1203 AM PST Mon Jan 5 2026 (Today and tonight) In a word, wet. The next organized band of showers will move through with the passage of a cold front today. The current radar data shows a pretty well-behaved warm sector rain band coming into range. There have been a few lightning strikes over the ocean behind the front near a mature extratoprical cyclone. It's unclear if the convection will be as deep over land where the instability is weaker, but this low pressure system will enhance the rain to some degree this afternoon. The North Bay will be hit the hardest today, with 1-2" expected in the lower elevations, and up to 4" in the mountains. The rain will start there as early as 2 AM, and continue off-and-on through the entire day. Minor urban and small stream flooding is expected, and there is a slight chance for the larger rivers to reach minor flood stage. The rest of the Bay Area will get less rain. There's quite a bit of disagreement between the models on how much less, with high resolution guidance much drier than global models. Outside of the North Bay we could get anywhere from less than 1/10" or up to 3". The ECMWF ensemble spread ranges from 0.25" to 2.5" at SFO. That's a significant amount of uncertainty to put in the short term section, but with the heavier line of showers expected to stall somewhere along the coast, it makes sense. The IQR is more reasonable at 1-1.5", but the outlier members are just as likely as any other solution in the ensemble. Cut-off low pressure systems are hard to forecast because there is nothing obvious moving them along. It's like a toddler in a candy store that just let go of their parent's hand. Nobody knows what will happen. The exact track of this drifting feature will have a big influence on the rain totals today. The system should drift somewhere near the coast of the Bay Area this afternoon before becoming vertically stacked, drifting south, and weakening overnight. This will coincide with the passage of a sharp trough in the jet stream, flipping upper level winds nearly 180 degrees from SW to NE. That changes everything for the rest of the week. && .LONG TERM... Issued at 1203 AM PST Mon Jan 5 2026 (Tuesday through Sunday) In a word, dry. As the upper level winds flip to northerly following passage of the trough axis, drier, more stable air will start to move in. Tuesday is a transition day between the wet stormy pattern we've had for the last week, and much drier weather that arrives in earnest Wednesday. Before we get there, don't be surprised to see a couple showers on Tuesday, but nothing comparable to the last few days. There shouldn't be any more flooding concerns, especially after the sun comes up. A weak trough will move through on Wednesday, but shouldn't bring more than clouds. By Thursday, a 500 mb ridge will build and the skies will clear. The PW will drop below 0.4" (25th percentile), where it could stay for the next 2 weeks. The clear skies will bring cold morning temperatures with interior areas dropping into the 30s for the first time since late December. An inside slider pattern could develop and will bring some offshore winds this weekend before another ridge builds next week. && .AVIATION... (06Z TAFS) Issued at 937 PM PST Sun Jan 4 2026 Generally VFR conditions with mid- to high level clouds across the region, with isolated showers persisting early tonight. Widespread rain returns after Monday morning with generally moderate rain rates, particularly for the North Bay terminals, localized heavy rain, and diminished visibilities expected. Southerly flow continues through the TAF period, with winds remaining light overnight with periods of gusty winds expected as the main rain band comes through. Visibilities and ceilings will drop below the TAF forecast if a strong shower moves over a particular terminal. Vicinity of SFO... VFR with mid- to high level clouds through the next few hours before light to moderate rain returns Monday morning, when conditions hover near the MVFR-VFR threshold. Showers will again diminish in intensity Monday evening through the end of the TAF period as ceilings lift above MVFR thresholds. Visibilities and ceilings will drop below the TAF forecast if a strong shower moves over SFO. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals...Light winds overnight as generally VFR-MVFR conditions and isolated to scattered showers continue. Southerly winds build overnight as a frontal rain band approaches, with the main impacts arriving Monday morning, including gusty southeast winds and light to moderate rain. Rain intensity should diminish Monday afternoon through and after the end of the TAF period. If more intense showers develop over the region, expect visibilities and ceilings to drop below the forecast within the TAF. && .MARINE... (Tonight through next Saturday) Issued at 937 PM PST Sun Jan 4 2026 Isolated to scattered showers continue overnight with widespread rainfall and a slight chance for thunderstorms developing on Monday. Seas remain moderate to rough tonight under southwesterly winds with strong to gale force gusts. Winds diminish by early next week but are expected to build again, along with seas, during the late week as long period northwesterly swell returns. && .BEACHES... Issued at 1203 AM PST Mon Jan 5 2026 One last day of coastal flooding from king tides and storm surge. While lower than previous days, the high tide will still be roughly 1.2 feet above normal, bringing minor impacts to low-lying areas near shorelines and tidal waterways during high tide. The Coastal Flood Advisory is in effect through 3 PM today for the San Francisco Bay and San Pablo Bay. High tide is expected in San Francisco at 12:08 PM Monday. High tide timing varies up to 90 minutes later through the San Francisco Bay. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Coastal Flood Advisory until 3 PM PST this afternoon for CAZ006- 506-508. PZ...Small Craft Advisory until 9 PM PST this evening for Mry Bay. Small Craft Advisory until 3 PM PST this afternoon for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 9 PM PST this evening for Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 9 AM PST this morning for Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm. Gale Warning from 9 AM this morning to 3 PM PST this afternoon for Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory from 9 AM this morning to 9 PM PST this evening for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...DialH MARINE...DialH Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea