406
FXUS66 KSTO 011802
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1102 AM PDT Tue Sep 1 2026

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


.KEY MESSAGES...

  - Well below normal temperatures persist through this week.

  - Increasing confidence in wet weather this week, starting in
    Shasta County this evening into Wednesday with isolated
    thunderstorms and scattered showers, widespread north of I-80
    Thursday and Friday

  - Mainly dry Saturday, with the potential for some remnant
    tropical system moisture Sunday through early next week, but
    confidence in details remains low at this point, with showers
    south of I-80 currently forecast.

&&

.DISCUSSION...

Today to Wednesday...

Dry weather this morning, with low clouds and fog/low visibility
in the foothills where the clouds intersect with terrain. Forecast
high temperatures for today 15 to 20 degrees below normal as a
as a short wave trough moves in, with Valley highs generally in
the 70s. Some breezy onshore winds continue, south to southwest
winds, with gusts to around 20 mph in the Valley and Delta, up to
30 to 40 mph in the mountains. Fire concerns have decreased with
higher humidity levels, and this will be the case through the
week. There is the potential for isolated showers and
thunderstorms in the northwestern portion of Shasta County this
evening, continued to show by CAMS runs and a probability of
thunderstorms of 15%. The best potential for rain showers is over
Shasta County and into the northern Coast Range and into western
Plumas County and Lassen Volcanic National Park.

Thursday to Early Next Week...

The remainder of the week and into the weekend, troughing will
remain the dominant pattern, maintaining cooler than normal
temperatures and bringing more widespread precipitation.
Confidence and forecast rainfall amounts are increasing,
especially north of I-80, including into the Valley. The latest
storm totals have trended higher, ranging up to 2 inches over the
mountains of northern Shasta County, with the northern Sacramento
County seeing up to two thirds of an inch. Totals up to a three
tenths of an inch are forecast elsewhere in the Sacramento Valley
and the Delta. There is now a 15-20% probability of thunderstorms
Thursday in the mountains north of I-80, highest over the
mountains of Shasta County. An upper low spinning centered over
Oregon may have bring some weak disturbances in the mountains over
the weekend, but overall Saturday is trending dry. On Sunday the
center of the upper low passes along the California and Oregon
border, with slight chance of mainly Shasta County showers.

There is the potential for a tropical system to bring some moisture
into California early next week, but ensembles are showing many
different tracks, so confidence in precipitation potential from
this extending into interior Northern California remains fairly
low. Currently the best potential for rain is south of I-80 on
Monday, especially in the mountains.

&&

.AVIATION...
VFR conditions prevail over the next 24 hours across interior
NorCal. Valley south to west 10 to 15 kts in the afternoon with
gusts up to 20 to 25 kts with Sierra gusts up to 35 kts until 03z
Wednesday. Periods of haze and smoke exepcted across the forecast
area through 18z Wednesday.

&&

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

$$