, Issued at 235 AM PST Sun Dec 28 2025 (Today and tonight)
High clouds are visible on satellite imagery this morning, currently tracking into the Bay Area. This has made for an interesting forecast around these areas, particularly the North Bay where fog has developed. Pockets of colder air can be found there, but as of this time, not enough to warrant a Cold Weather Advisory. In fact, looking south to where the Cold Weather Advisory is in place, temperatures generally look to be on track. There is some concern for the low temperature forecast around the North Salinas Valley and areas near Hollister given dew points haven't really fallen past the upper 30s at this time. Depending on how temperatures pan out this morning, we may be able to end the Cold Weather Advisory early if temperatures don't fall.
Looking at the rest of today, high clouds continue to advance southwards. High pressure builds over the eastern Pacific which will pinch off part of the upper level trough. Highs today will be a few degrees warmer than yesterday. An area to watch will be Sunday night into Monday. Ridging continues to build in over northern California, and another upper level trough forms over the Sierra, gets cut off, and then pushes into southern California. This should allow for mostly clear skies and perhaps some weak overnight offshore flow. The low temperature forecast will be the other challenge in the near term. Right now we flirt with Cold Weather Advisory conditions over the North and East Bay valleys, as well as the southern Salinas Valley. Given some of the guidance from the MOS has trended a bit warmer, opted to not issue anything this far out. The coldest temperatures from these areas look to be between roughly around 12- 15Z, before warming above criteria by late morning.
..issued at 235 AM PST Sun Dec 28 2025 (Monday through Saturday)
Ridging holds through Tuesday, before it gets pushed over the PacNW. To the north, low pressure from the Gulf of Alaska forms and begins to digs southwards. To the south, the cut of low meanders and slowly drifts northward. This system should get picked up by digging trough to our north. Ensembles favor wetter weather starting Wednesday, with the QPF clusters showing a spread of rain solutions across California. The NBM guidance matches this, thus opted to leave that in. Looking at the GEFS and ECMWF ensemble, periodic rounds of rain look possible through the weekend. Timing, placement, and intensity
(06z TAFS) Issued at 935 PM PST Sat Dec 27 2025
The larger scale WMC-SFO pressure gradient will strengthen tonight through Sunday night resulting in offshore winds reaching the Bay Area. A mainly clear sky will help with radiative cooling and patchy fog redevelopment tonight and Sunday morning. Will also have to monitor tule fog redevelopment in the Central Valley and the potential for a return of tule fog into the Bay Area, though at the time being the HRRR model shows greater tule fog development Sunday night into Monday. The offshore winds develop before then, tule fog development and transport of tule fog could start as soon as early Sunday morning due to recent rains and moistened boundary layer. KSTS and KAPC have fog in the TAFs due to nocturnal radiative cooling, otherwise it's a moderate to high confidence VFR forecast for the remainder of the terminals.
Vicinity of SFO, VFR. Mainly northeast winds 5-7 knots tonight through Sunday night.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR. Winds east-southeast 5-10 knots and continuing into early-mid Sunday afternoon, then becoming light and variable to light onshore in the late afternoon. Light east to southeast winds redevelop Sunday night.
(12Z TAFS) Issued at 336 AM PST Sun Dec 28 2025
Very quiet conditions with VFR expected through the TAF period for most terminals. Exceptions will be North Bay terminals where isolated FG is anticipated during the pre-dawn hours. Light offshore NE flow keeps most other locations dry with light winds. Generally a high confidence forecast, exception is how long the FG persists (or not) at KSTS/KAPC.
Vicinity of SFO, VFR. Winds out of the NE for most of the period, but expected to remain light and not impactful.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR. Light offshore winds. High confidence.
(today through Friday) Issued at 336 AM PST Sun Dec 28 2025
Light northerly breezes, moderate seas, and high pressure prevail through the first half of this week. Next chance for showers over the waters by the end of the week as a low pressure system moves in from the south.
Ca, Cold Weather Advisory until 9 AM PST this morning for CAZ516>518- 528.
PZ, None.
