South Yuba City, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

332
FXUS66 KSTO 242130
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
130 PM PST Wed Dec 24 2025

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


.KEY MESSAGES...

 - Major holiday travel impacts from periods of heavy rain,
   thunderstorms, heavy mountain snow, and gusty winds through
   Friday.

 - Heavy snow is expected today and Thursday, with snowfall rates
   of 1-2" per hour at times.

 - Periods of heavy rainfall are anticipated across the Valley and
   lower foothills with additional flood impacts possible through
   Friday.

 - Strong southerly winds are expected later this evening and
   through Thursday, with wind gusts of 40-60mph.

&&

.DISCUSSION...

...Today through Friday...

Current satellite and radar has a band of moderate to heavy
precipitation moving through the mountains, with snow levels
sitting around 5000 feet. We expect the Valley to see a lull in
activity through today, with increasing coverage and intensity of
precipitation later this evening and overnight. Snow levels will
continue to drop through the day, reaching 4500-5500 feet
this evening. Snowfall rates anywhere between 1 to 2 inches per
hour at higher elevations, with totals ranging from 4-8 feet above
5500 feet within the Sierra and up to a foot around 4500-5500
feet. Isolated higher amounts at the higher elevations. In the
Coastal range and southern Cascades, snow levels will continue to
drop to near 3500-4500 feet tonight and tomorrow. Snow totals
range between 1-3 feet above 4500 feet, and up to a foot around
3500-4500 feet.

CAMS have another wave of precipitation developing later this
evening and pushing through region. Moderate to heavy rain,
scattered thunderstorms (with a few isolated stronger storms),
strong southerly winds, and continued heavy mountain snow as the
next wave of precipitation moves through. Guidance shows several
waves of precipitation moving through as the surface low pressure
system moves onshore, with low level shear, strong moisture pull
from the eastern Pacific, and up to 500 MUCAPE. There will be a
slight chance for a few isolated stronger storms developing as the
wave of precipitation moves through the region. A stray severe
storm can`t be ruled out. The main timeframe for any stronger
storms would be around 01-05z when instability, shear, and sfc
vorticity is at its peak in the area.

We are currently in a lull in activity for the strong southerly
winds today, but as the wave of precipitation moves onshore winds
will start to increase once again. Through the area wind gusts
approach 40-60 mph this evening, overnight, and through Thursday.
If you have decorations and loose outdoor objects outside, make
sure to tie them down as they are likely to blow around. A High
Wind Warning remains in effect for the Valley and adjacent
foothills through 4pm Thursday.

Rain rates approach an inch per hour at times as the
precipitation moves through the area. Areas around Shasta County
will be monitored as a convergence zone may redevelop this
evening. Precipitation will be scattered to widespread through
Christmas Day and Friday. The Flood Watch remains in effect
through Friday, with the exception of the Sierra where
precipitation has transitioned over to snow. Thus we cancelled the
Flood Watch for the Sierra.

Major travel impacts are expected through Friday,
from mountain snow, strong gusty winds, and rainfall across the
area. A combination of dangerous mountain travel conditions from heavy,
wet snow and gusty winds and periods of difficult travel at lower
elevations from heavy rain, gusty winds, and thunderstorm chances
are likely through Friday. If you have travel plans this week
plan ahead, make alternate routes, have backup plans, and carry
safety kits with you in case of an emergency. If you see flooded
areas, turn around don`t drown.

...Saturday and onward...

Lingering Minor impacts within the mountains are expected on
Saturday as lingering snow and gusty winds continue to impact
travel. However, by Sunday chances for precipitation dwindle and
conditions dry out for the region. Long range guidance has picked
up on dry conditions continuing thorough the early portions of
next week and potentially into the New Year. There will also be
chance for low stratus to redevelop across the Valley early next
week bringing low ceilings and visibilities at times.

&&


.AVIATION...

MVFR/VFR conditions through 00-03z turning IFR/MVFR as
moderate to heavy precipitation moves through bringing low
visibilities, chances for thunderstorms, and strong winds. Wind
gusts reach 35-45kts for each site around 04-06z and continues
through the end of the TAF period. LLWS during this time as well
of 45-50kts. Snow levels will continue to drop through the TAF
period toward 4500-5500 feet in the Sierra and 3500-4500 feet in
the Coastal range and southern Cascades.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday afternoon for Carquinez Strait and
Delta-Central Sacramento Valley-Motherlode-Mountains
Southwestern Shasta County to Western Colusa County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Shasta Lake Area / Northern Shasta County-
Southern Sacramento Valley.

Winter Storm Warning until 10 PM PST Friday for Burney Basin /
Eastern Shasta County-Mountains Southwestern Shasta County to
Western Colusa County-Shasta Lake Area / Northern Shasta County-
West Slope Northern Sierra Nevada-Western Plumas County/Lassen
Park.

High Wind Warning until 4 PM PST Thursday for Carquinez Strait
and Delta-Central Sacramento Valley-Motherlode-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Northern
San Joaquin Valley-Southern Sacramento Valley.

&&

$$