FXUS66 KMTR 302204 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 204 PM PST Tue Dec 30 2025 ...New SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 202 PM PST Tue Dec 30 2025 - Rain returns and becomes widespread for New Years Eve - Friday is likely to be windy with strong southerly winds along with locally heavy rainfall - Coastal flooding from King Tides is expected Wednesday through Sunday - Unsettled conditions look to prevail through at least early next week && .SHORT TERM... Issued at 202 PM PST Tue Dec 30 2025 (This evening through Wednesday) Temperatures are struggling to warm this afternoon as low clouds remain trapped beneath the high clouds advecting north across the region this afternoon. As of this writing, temperatures remain in lower-to-mid 40s in much of the North Bay and East Bay valleys. However, coastal areas have warmed into the 60s and even lower 70s across the Central Coast where offshore flow persists. That said, minimum temperatures overnight are forecast to be warmer than previous nights as increased moisture and cloud cover continue to spread northward in advance of an approaching weather system. By Wednesday morning much of the Central Coast will be experiencing light to moderate rain that will then spread northward across the Bay Area and North Bay throughout the afternoon and evening. However, locally higher amounts are expected in the Santa Lucia and Sierra de Salinas ranges where there is a marginal risk for excessive rainfall on Wednesday and Thursday due to orographic lift. Given the recent rainfall, this will lead to nuisance flooding for poor drainage areas, urban areas, and rises on flashy creeks/streams. && .LONG TERM... Issued at 202 PM PST Tue Dec 30 2025 (Wednesday night through next Monday) Rain will continue on New Years Day, yet not as heavy or widespread as Wednesday as the mid/upper level cut-off low pushes inland over southern California. By Friday, an atmospheric river is forecast to move across the North Bay and then progress southward bringing additional rainfall to the region and a 10-15% chance for thunderstorms. This is when we are expecting the heaviest of rainfall, however the boundary does not appear likely to stall at any given point. There is a marginal risk for excessive rainfall on Friday across the interior Bay Area and Central Coast. Southerly winds will also be strong and gusty on Friday, especially ahead of and along the main frontal boundary that is forecast to move through the Bay Area and Central Coast Friday afternoon and evening. Gusts are currently forecast to be 45-55 mph along the coast, in the higher terrain, and northwest to southeast oriented valleys. Elsewhere expecting 35-45 mph gusts from late Friday morning through the evening and potentially into early Saturday morning. Rainfall amounts and wind speeds will be better refined as we get closer to the event. Unsettled conditions look to prevail into the weekend and potentially into early next week as the pattern aloft remains troughy. && .AVIATION... (18Z TAFS) Issued at 930 AM PST Tue Dec 30 2025 Fog and low stratus persist in the North and East Bay valleys through 19-20Z. Otherwise, the region is generally VFR with extensive mid- to high-level clouds developing across the region through the day. Gentle to moderate offshore breezes will prevail through the day with little chance for showers through the day. Overnight, winds will relax, and the incoming high clouds will aim to disrupt radiative cooling and stratus development. Confidence in the forecast for fog at STS tonight has decreased, but opted to leave the TAF intact for now. Showers will build in from the south on Wednesday morning and spread throughout the region through the day. Vicinity of SFO... Generally VFR with mid- to high level clouds through the TAF period, with a gentle northeast breeze through the day. Ceilings will lower Wednesday morning in advance of showers expected to arrive late in the morning through the end of the TAF period. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals... Gentle to moderate southeast breezes developing through the day with mid- to high level cloud ceilings. Winds will relax overnight in advance of showers arriving in the pre- dawn hours Wednesday morning. && .MARINE... (Today through Sunday) Issued at 921 AM PST Tue Dec 30 2025 Moderate to fresh east to northeast winds and moderate seas prevail through Wednesday. Fresh to strong southerly breezes return Thursday into Friday with gale force gusts likely. Seas build to become rough Thursday into Friday. Rain returns Wednesday and lasts through the weekend into the early part of next week. && .BEACHES... Issued at 925 PM PST Mon Dec 29 2025 Perigean spring tides (King Tides) return Wednesday - Sunday. This is due to the combination of the full moon on 1/3, lunar perigee on 1/1, and perihelion on 1/3. In other words all three planetary bodies are lined up and close to each other. In addition to the high astronomical tide, the incoming low pressure system will bring strong onshore winds, generating some storm surge. The combination of these factors will bring minor coastal flooding to the low-lying areas near shorelines and tidal waterways during high tide Wednesday through Sunday. At the San Francisco tidal gauge, high tide is expected to be 1.5 ft above normal at 7:51 AM Wednesday, 1.7 ft above normal at 8:41 AM Thursday, 1.8 ft above normal at 9:34 AM Friday, 1.8 ft above normal at 10:26 AM Saturday, and 1.6 ft above normal at 11:18 AM Sunday. These predictions include 0.5 feet of storm surge that will enhance the astronomical tide and flooding threat. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Coastal Flood Advisory from 5 AM Wednesday to 2 PM PST Sunday for CAZ006-505-506-508-509-529-530. PZ...None. && $$ SHORT TERM...RGass LONG TERM....RGass 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