749 FXUS66 KMTR 310601 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1001 PM PST Tue Dec 30 2025 ...New AVIATION, MARINE... .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 && .UPDATE... Issued at 740 PM PST Tue Dec 30 2025 Deeper cloud features streaming in from the south, evident via current satellite. Still a pretty remarkable dry layer in the low-to-mid levels of the atmosphere, so any precipitation that may fall out of the clouds overnight will have some work to do to cool and moisten that layer. By mid-morning tomorrow, the dry air will likely be overcome, giving way to a few showers beginning along the Central Coast. We'll need to watch more closely going into the evening and overnight hours tomorrow when a more vigorous upper level wave is progged to move across the Central Coast, alluding to a chance of isolated thunderstorms. Otherwise no major updates to the forecast for the upcoming storm system. Behringer && .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... (06Z TAFS) Issued at 929 PM PST Tue Dec 30 2025 LIFR/IFR visibility is expected to prevail at KSTS through the overnight into mid-morning, with LIFR/IFR cigs expected for KAPC and lower confidence on visibility there. Area cameras attm show patch areas of limited visibility but not below half-mile. VFR is for the remaining terminals through the overnight and much of the daytime hours Wednesday. Vicinity of SFO...VFR expected through the overnight and daytime hours Wednesday. Scattered showers moving up the Pacific coastline Wednesday evening through the remainder of the TAF period have the potential for MVFR ceilings and slight chance of an isolated thunderstorm. Confidence for isolated thunderstorm is currently too low for mentioning in the TAF but could limit visibility along with strong erratic wind gusts. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR is expected to prevail overnight. There is a chance for MVFR cigs by late morning if as a coastal storm moves north just offshore. Once MVFR/IFR cigs are established, they're expected to persist through the remainder of the TAF period. && .MARINE... (Tonight through next Monday) Issued at 929 PM PST Tue Dec 30 2025 Moderate seas with moderate to fresh northeast winds will persist through Wednesday, with southerly breezes Thursday, ramping up quickly overnight Thursday into Friday when widespread gale force gusts spread across our outer and inner waters. There is also a slight chance of isolated thunderstorms Wednesday and Thursday, with higher confidence on Friday. Winds gradually ease overnight into Saturday becoming southwesterly. && .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...JM MARINE...JM 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