829
FXUS66 KSTO 242156
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
256 PM PDT Thu Sep 24 2026

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


.KEY MESSAGES...

   - Periods of Elevated Fire Weather Conditions for portions of
     interior NorCal into early next week due to breezy winds and
     low humidities.

  - Areas of Moderate HeatRisk in the Northern San Joaquin Valley
    into this evening.

  - Low chances (around 10%) for isolated showers for
    northwestern Shasta County tonight into Friday. Otherwise,
    primarily dry weather continues into next week.

  - Periods of breezy to gusty winds Friday through early next
    week.

&&

.DISCUSSION...

...Today-Tonight (9/24)... Sunny skies are being observed across
Northern California this afternoon, with just some thin cirrus
clouds ahead an approaching trough with a weakening cold front.
Temperatures for the week peak today, this afternoon currently
reaching the upper 80s to low 90s across the Valley, warmest in
the northern San Joaquin Valley, where there are areas of Moderate
HeatRisk. Winds are light now, but onshore flow will increase in
the Delta and over the mountains this evening tonight as a trough
passes to the north, through the Pacific Northwest.

While the trough passage will be dry for the vast majority of the
area, there is a low, nonzero chance (around 10%) of isolated
showers along the northwestern edges of Shasta County this evening
into early Friday. Most of the rain is expected to remain farther
north and west.

...Friday-Sunday (9/25-9/27)...
The trough will bring additional periods of breezy to gusty winds
Friday into Saturday, with winds mainly out of the west-
southwest on Friday, then shifting out of the north northeast on
Saturday for the northern and central Sacramento Valley and
adjacent mountains and foothills, with gusts in those areas 20 to
30 mph. On Saturday the combination of gusty winds and low
afternoon humidity percents in the upper teens to low 20s bring a
several hours of elevated fire weather conditions.

Additional periods of breezy to gusty southerly flow area
expected on Sunday as the trough deepens and pushes through
Northern California, mainly over the Sierra. Models continue to
favor a continued dry pattern, though the pattern suggests the
we can`t rule out the possibility of stray mountain showers.

...Monday-Wednesday (9/28-9/30)...
Periods of breezy northerly flow are forecast to develop on
Monday through the Sacramento Valley as the aforementioned trough
tracks over the Desert Southwest, with downsloping northeasterly
to easterly winds over the Sierra. Breezy north winds through the
Valley and downsloping winds in the Sierra are favored on Tuesday
as well. These will bring the potential for more significant
elevated fire weather conditions. Temperatures remain on track to
trend warmer through the week as weak ridging builds over
interior NorCal.

&&

.AVIATION...

VFR conditions continue through the rest of today and into
tonight, with mostly clear skies. Sustained winds will be
generally less than 12 kts. Breezier Delta winds are expected
tonight into Friday through 18Z.

&&

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

$$