848
FXUS66 KSTO 161915
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1215 PM PDT Wed Sep 16 2026

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

.KEY MESSAGES...

  - Cooler weather, breezy onshore winds, and increased humidity
    through Thursday

  - Isolated thunderstorm chances through Thursday, mainly across
    Coast Range, Shasta County, and southern Cascades

  - Warming and drying conditions late week and over the weekend
    with near normal temperatures

&&

.DISCUSSION...

Today-Thursday:
Current GOES-West visible satellite imagery shows some cumulus
clouds developing over the mountains mainly north of Interstate 80
so far on this Wednesday afternoon. The few low clouds that made
it into the Valley this morning have dissipated. Surface
observations are showing temperatures currently trending
approximately 5 to 10 degrees cooler than this time yesterday
afternoon.

The upper level pattern will feature an area of low pressure over
northern California bringing unsettled weather to northern
portions of the forecast area today and Thursday. There is a 15 to
20 percent chance for isolated thunderstorms over the Coast Range,
Shasta County and southern Cascades this afternoon and evening
and again on Thursday. Storms generally are expected to come with
some moisture, however lightning, especially outside the main
precipitation core will lead to fire weather concerns for any
potential fire starts. With any thunderstorms that develop,
additional potential impacts would be brief heavy rain, small
hail and gusty winds. When thunder roars, go indoors!

Dry conditions are expected elsewhere for the rest of interior
northern California. Temperatures across the forecast area will also
trend cooler and below normal for mid September climatology over
this period. High temperatures are forecast to be in the 70s to
80s in the Valley and foothills, and 50s to 70s in the mountains
today and Thursday. Higher humidity and breezy onshore winds are
also expected. A stronger onshore push Thursday morning may bring
more marine stratus intrusion to the Central Valley before
dissipating late morning.

Friday-Early Next Week:
High pressure builds back in Friday and Saturday bringing
temperatures up closer to normal for this time of year. Dry
conditions with lower humidity are also anticipated, along with
weak offshore (N to E) flow. Ensemble guidance then indicates some
form of upper low off the coast Sunday or early next week bringing
a period of onshore flow and slightly cooler temperatures before
the ridge builds back in. As always, be sure to check the
forecast at weather.gov/sacramento for any updates!

&&

.AVIATION...
VFR conditions continue at TAF sites through 06z Thursday with
increasing potential for MVFR/isolated IFR cigs in low stratus
through the remainder of Thursday AM. Highest chances for low
stratus development (50-80%) are forecast for the Sacramento metro
and Valley points northward toward RDD. Otherwise, breezy south
to west winds persist through 06z, gradually falling below 12 kts
area wide overnight. Strongest gusts 15 to 25 kts expected through
the Delta and into the Valley vicinity.

&&

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

&&

$$