211
FXUS66 KSTO 122146
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
146 PM PST Fri Dec 12 2025

For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.

.KEY MESSAGES...

 - Persistent low clouds, mist, fog and unseasonably cool high
   temperatures continue in the Central Valley, Delta and lower
   foothills with minimal change through the weekend

-  Well above normal temperatures continue above the stratus layer
   for higher terrain through this weekend with low humidity

-  Increasing confidence in a pattern change next week to
   unsettled weather, with chances for precipitation and breezy
   winds

&&

.DISCUSSION...

...Today - Sunday...
Current GOES-West visible satellite imagery illustrates a blanket
of fog, mist and low clouds across the Central Valley, Delta and
lower foothills once again on this Friday afternoon. Broad high
pressure will continue to be the primary synoptic influence for
the region through the weekend, and little change is expected each
day. Fog, mist and low clouds will persist through the weekend
for much of the same area. High temperatures for the lower
elevations will be in the 40s, which is trending about 10 degrees
cooler than normal for mid December climatology. The opposite is
true for higher terrain above the stratus layer, where highs are
in the 50s to low 70s, which is about 20 degrees warmer than
average for this time of year. Only very minor cooling is expected
in the mountains through the weekend as high pressure begins to
shift eastward. Be sure to take is slow and use low-beam
headlights if dense fog is encountered while driving!

...Next Week...
Confidence is increasing in a pattern change next week,
transitioning from high and dry with persistent stratus, to
wetter and breezier. Latest guidance indicates precipitation
first moving into Shasta County late on Monday, and then spreading
southward across our forecast area on Tuesday and continuing into
Wednesday. The latest rain forecast has trended slightly wetter,
mainly for Shasta County and the mountains. The National Blend of
Models (NBM) also indicates a 10 to 15 percent chance of
thunderstorms Tuesday afternoon through Tuesday night. Best
chances are currently over the north/central Sacramento Valley,
northeast foothills and over the mountains. Little to no snow
accumulations are currently expected, as snow levels are fairly
high with this round (above 7000-8000 ft). Motorists should slow
down and drive with caution if slick roads are encountered while
driving next week. Extended models are also indicating several
waves of precipitation possible as we progress later into the
month of December. The latest Climate Prediction Center 8 to 14
Day Probabilistic Outlook favors above normal precipitation for
December 20-26. Be sure to check back with us for updates as we
get closer!

&&

.AVIATION...
Persistent low ceilings and reduced visibility across the Central
Valley and lower foothills over the next 24 hours with IFR/LIFR
conditions, although some TAF sites may very briefly see MVFR/VFR
visibility around 23-03Z. Another round of BR/FG and low stratus
returns after 00Z-06Z with areas of IFR/LIFR ceilings once again
expected to persist into Saturday. Light and variable surface
winds less than 10 kts.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$