419
FXUS66 KSTO 092148
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
148 PM PST Tue Dec 9 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. Fog in the northern Sacramento Valley has diminished
this afternoon, but lingers in the foothills. 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 area. Winds remain generally light and variable.

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
little to no impacts are expected at this point. This system could
potentially end this stagnant pattern. Stay tuned for forecast
updates.

&&

.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 03Z-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.
&&

$$