116
FXUS66 KSTO 092033
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1233 PM PST Fri Jan 9 2026

.KEY MESSAGES...

 - Dry weather expected next 7 days with areas of patchy morning
   fog and cold overnight/morning temperatures through the
   weekend.

 - Increasing potential for a return to more widespread Valley
   fog/low clouds and warm/dry weather at higher elevations into
   next week.

&&

.DISCUSSION...

...Rest of Today into the Weekend...
Current satellite imagery from early this afternoon shows mostly
clear skies across interior NorCal as ridging aloft is beginning
to build into the region. As a result, similarly seasonable
temperatures persist today, before plunging toward the teens and
20s at high elevations and lower 40s to near freezing in the
Valley and foothills overnight into Saturday morning. Widespread
frost at low elevations is still not anticipated, but patchy frost
will remain possible, especially in typically cooler locations.
As lighter, but still breezy, north winds continue today, Valley
fog development is expected to remain patchy into Saturday with
current probabilities of visibility less than a half mile around
20 to 40 percent.

Through the weekend, the ridging feature aloft will continue
building in over the West Coast, although it is not expected to
settle in place until early next week. A weak shortwave passing
well to the north of the area will provide some sporadic high
cloud cover throughout the weekend, with minimal direct impacts
anticipated. This cloud cover may mitigate further fog
development, however, with similar 20 to 40 percent probabilities
for Valley fog into Sunday morning.

...Next Week...
As the aforementioned building ridge aloft finally settles in and
amplifies over the west coast by next week, a stagnating weather
pattern is expected to persist throughout the extended forecast
period. While some details regarding wind and surface moisture
will likely impact initial fog development, this arriving pattern
will be favorable for a return to widespread Valley fog/low clouds
and warm/dry weather at higher elevations. Where fog/low clouds
do not develop or dissipates earlier in the day, warm, above
normal temperatures will be likely given the expected amplitude of
the building ridge. Additionally, breezy to gusty terrain driven
winds, strongest overnight and early morning, will remain
persistent at higher elevations. Ensemble guidance does indicate
potential for additional northward ridge amplification late next
week, which would bring breezier north winds to the Valley and
possibly disrupt the fog/low cloud pattern.

&&

.AVIATION...

VFR conditions prevail through the afternoon and evening hours,
with BR/FG moving in around 08z through 10z. Best chances for FG
will be in SCK and MOD, with lower chances near RDD and RBL.
Visibility reductions near and around FG when it develops. FG
starts to dissipate after the TAF period (tomorrow afternoon).
Winds will be light and variable through the TAF period.

&&

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

$$