381
FXUS66 KSTO 181912
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1212 PM PDT Sat Jul 18 2026


.KEY MESSAGES...

 - Elevated fire weather concerns in the northern Sacramento
   Valley into the adjacent northeastern foothills this afternoon
   and evening.

 - Chances for monsoonal moisture and thunderstorms Sunday into
   midweek next week.

&&

.DISCUSSION...

Mostly clear skies throughout the day, with breezy conditions at
times as south to southwesterly flow remains in place aloft across
California. Breezy winds combined with low relative humidity
values in the northern Sacramento Valley to adjacent northeastern
foothills brings elevated fire weather concerns this afternoon and
evening. Conditions improve after the sun sets and conditions cool
off.

There is a slight chance for an isolated shower or storm along the
Sierra Crest south of Highway 50 this evening. However, the
instability, moisture, and lift are closer toward Nevada and into
areas south of the forecast region. Otherwise, expect more
seasonal temperatures today, with highs in the 90s across the
area. Delta winds increase this evening helping to cool off parts
of the northern San Joaquin Valley and southern Sacramento Valley
near sunset.

Monsoonal moisture returns to the region Sunday, with PWATS
increasing across parts of California. Current HIRES guidance has
isolated shower and thunderstorm chances within the Sierra Sunday
morning, with potential for further development in the northern
Sacramento Valley towards the southern Cascades, Coastal Range,
and northeastern Sierra by the afternoon. Confidence in morning
activity within the Sierra is higher, due to more upper level lift
and instability. During the afternoon/evening and overnight hours
confidence is lower due to the lack of lift across the northern
forecast area and diminished elevated instability after morning
isolated storms. Guidance has struggled on the development any
thunderstorm or even shower development. Chances are around 10
percent for areas in the northern Sacramento Valley toward the
adjacent higher terrain Sunday afternoon/evening and overnight.
Majority of the shower and thunderstorms that develop will be wet,
but a few may be dry.

Continued monsoonal moisture Monday through mid next week, with
thunderstorm chances predominantly in the afternoon and evening
hours within the Sierra. We will monitor the chance for any dry
thunderstorm during this time, but right now confidence is low.
Otherwise, expect more seasonable temperatures to continue through
next week.

&&

.AVIATION...

VFR conditions through the TAF period, with breezy conditions in
the Delta around 21z through 12z. A few gusts up to 25kts during
this time frame. Sacramento sites see breezy conditions at times,
with 15-20kts gusts possible this afternoon and evening.
Otherwise, lingering clouds this afternoon and clearing in the
evening and overnight. A FEW to SCT clouds around 10-16z tomorrow.

&&

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

&&

$$