596
FXUS66 KSTO 102120
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
120 PM PST Wed Dec 10 2025
.KEY MESSAGES...
- Periods of low clouds, mist, fog and unseasonably cool high
temperatures continue in the Central Valley, Delta and lower
foothills this week with little change
- Increasingly mild temperatures with sunny skies and dry
weather are expected over higher terrain this week
- Potential for a pattern change next week with light
precipitation, but uncertainty is high and might be limited to
the far northern area in Shasta County
&&
.DISCUSSION...
...Today - Sunday... Eastern Pacific high pressure ridging
continues a stagnant pattern across the region, with a strong
inversion keeping mist, fog and low stratus over the Valley and
Delta and into the lower foothills. Patchy fog has primarily been
observed over the northern Sacramento Valley and in the foothills
(1500-2000 feet) where low clouds are intersecting with the
terrain. This pattern is expected to continue with low clouds
persisting and some patchy fog reforming in the Valley again
tonight, most likely around the Redding to Red Bluff area. Winds
remain generally light and variable. As of 1pm today, conditions
are improving, particularly over the N. Sac Valley with patchy fog
and stratus lingering into the afternoon and evening.
This pattern is expected to persist through the week and even into
the weekend as the high pressure ridge continues to build. Dry
weather continues across the region. The exception to this is
periods of mist and drizzle at times with the low clouds and fog,
which may wet the ground.
The low clouds continue to keep high temperatures unseasonably
cool in the Valley and Delta, generally 10-14 degrees below
normal, while higher terrain experiences sunny skies and above
normal temperatures (10-20 degrees above normal). The building
high will bring further warming temperatures to the area over
higher terrain, generally for locations above 1500 feet. Stratus
and fog will prevent this warming for portions of the Valley and
Delta that remain covered, though, so little change in is expected
in those areas this week, with unseasonably cool temperatures
persisting. The northern Sacramento Valley has the best potential
for seeing some clearing due to a thinner cloud deck and some
light northerly winds late in the week, which could bring a
gradual increase in temperatures there locally.
...Next Week...
A pattern change is projected for early next week, but there
remains quite a bit of uncertainty in the timing and intensity of
this system. Current forecast shows the potential for
precipitation north of I-80, especially for the mountains. The
best chances expected over the mountains of Shasta County, but
minor to little to no impacts are expected at this point. This
system could potentially end this stagnant pattern and begin a
period of unsettled, but not significant weather. Stay tuned for
forecast updates and changes to the forecast.
&&
.AVIATION...
Lingering low cigs and mist across the Central Valley continue
into this evening with IFR/LIFR conditions, although some sites
may very briefly see MVFR/VFR visibility around 22-24Z, mainly for
TAF sites north of Sacramento. Another round of BF/FG and low
stratus returns after 00Z-06Z with areas of IFR/LIFR ceilings
once again expected to persist through the day. Light and variable
surface winds less than 12kts.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
