FXUS66 KMTR 151146 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 346 AM PST Mon Dec 15 2025 ...New SHORT TERM, LONG TERM, MARINE... .KEY MESSAGES... Updated at 343 AM PST Mon Dec 15 2025 - Dense fog will continue to impact bayshore, coastal, and valley locations through the morning - Wet weather returns late today and persists through the week and likely into next week && .SHORT TERM... Issued at 343 AM PST Mon Dec 15 2025 (Today and tonight) Today will start off foggy once again for bayshore, coastal, and valley locations. Low visibility could make driving conditions hazardous. If driving, slow down, use your low-beam headlights, and leave plenty of distance ahead of you. If commuting, allow extra drive time to reach your destination safely. A change is on the way though! In fact it can be seen in the form of high clouds streaming in from the west. These high clouds are associated with a storm force low off the coast of the Oregon/Washington border that is headed to British Columbia. The accompanying cold front will lose steam as it approaches the area, all but becoming stationary. While rainfall is possible as early as tonight, it will more than likely have to wait until tomorrow. This is when some form of upper-level support (longwave trough) skirts the region. The aforementioned feature will act to sweep through what is left of the first cold front by bringing a gale force low and its attendant cold front along with it. Rainfall will be light and beneficial, generally remaining confined north of the Golden Gate with the Central Coast remaining dry outside of maybe some coastal/higher terrain drizzle. Probably of more interest is that this pattern change will finally put at least a temporary end to the gloomy days as the atmosphere becomes too turbulent to support radiation fog. && .LONG TERM... Issued at 343 AM PST Mon Dec 15 2025 (Tuesday through Sunday) Some lingering rain showers are possible Wednesday and Thursday, but generally speaking it will be dry. The next system arrives Friday as a surface low pressure system enters into Northern California. The attendant cold front will become a stationary front Saturday into Sunday. This will be the thing to watch as stationary fronts offer an area of convergence and are a conveyor belt of moisture. Still, as of now, everything this week seems beneficial, especially coming off of a notable dry spell for November/December. When all is said and done, the official rainfall total forecast for the week (Monday through Sunday) has 2.50"-4.00" for the higher terrain of the North Bay, 1.25"-2.50" for North Bay Interior Valleys, 0.50"-1.25" for the East Bay, South Bay, San Francisco Peninsula, and Central Coast, and 0.50" or less for the Interior Central Coast. The Climate Prediction Center continues to highlight a moderate risk for precipitation Monday, December 22nd through Friday, December 26th, moderate risk for high winds Monday, December 22nd through Sunday, December 28th, and a high risk for precipitation for the North Bay Monday, December 22nd through Thursday, December 25th. All of the rainfall that we receive this preceding week will undoubtedly play a role in potential impacts next week. && .AVIATION... (06Z TAFS) Issued at 925 PM PST Sun Dec 14 2025 Patchy low clouds and fog are beginning to fill back in over the region. Low cigs and locally dense fog is expected once again tonight. Models indicate cigs will scatter out around 17z-19z. However high clouds drifting in over the region may help mix out the boundary layer a bit resulting in some earlier clearing Monday morning across area terminals. Vicinity of SFO...VFR conditions prevail currently however areas of patchy low clouds are anticipated to fill back in over the bay tonight. Confidence is low as to the extent of coverage impacting SFO and OAK. Models indicate cigs may stay out of SFO and OAK however satellite imagery indicates rapid spread close to the terminals and will need to watch closely. SFO Bridge Approach...Low clouds over the approach expected to fill in overnight with locally dense fog. Monterey Bay Terminals...IFR cigs will prevail through tonight with clearing anticipated after 17z Monday morning. && .MARINE... (Today through Saturday) Issued at 343 AM PST Mon Dec 15 2025 Southerly flow will prevail north of Pigeon Point ahead of an approaching frontal system. Conditions are ideal for dense fog across the bays and clearing may be slow today from the San Francisco Bay to the West Delta. Mainly light winds will prevail across the coastal waters except northwesterly winds becoming gusty across the southern coastal waters today to Tuesday. Winds will become gusty with increasing rain chances over the northern waters mid-week. Light seas will gradually build becoming moderate to rough by mid week. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Dense Fog Advisory until 11 AM PST this morning for CAZ506-508- 510-513-516-528>530. PZ...Dense Fog Advisory until 11 AM PST this morning for Mry Bay-SF Bay N of Bay Bridge. Small Craft Advisory from 3 PM this afternoon to 3 PM PST Tuesday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Sarment LONG TERM....Sarment AVIATION...CW MARINE...Canepa 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