708
FXUS66 KSTO 272028
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
128 PM PDT Sun Sep 27 2026

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



.KEY MESSAGES...

   - Periods of breezy to gusty winds through early this week.

   - Elevated Fire Weather Conditions for portions of interior
     NorCal on Monday through Wednesday due to breezy north to
     east winds and low humidities.

   - Chance for showers Monday for the Sierra crest south of
     HWY-50 (20-30%), 10% chance of isolated thunderstorms.

&&

.DISCUSSION...

...Today- (9/27)... Mostly cloudy skies this morning are giving
way to mostly sunny skies this afternoon as a mainly dry trough
moves through, bringing onshore flow cool temperatures. Radar
shows some virga (elevated rain that evaporates before hitting
the ground), but can`t rule out a few sprinkles or a brief light
shower. Highs in the upper 70s to near 80 are expected this
afternoon in the Valley, about 7 to 10 degrees below normal.

...Monday-Wednesday (9/28-9/30)... Periods of breezy northerly
flow are forecast to develop on Monday through the Sacramento
Valley as the trough closes off into a low and tracks southward
and eastern Pacific ridging builds in to the north. These winds
along with low humidity will bring elevated fire weather
conditions by afternoon, mainly to the northern Sacramento Valley.
While most of the area will remain dry, a slight chance of a
shower/t-storm remains in the forecast Monday afternoon and
evening on the Sierra crest south of HWY-50, with best potential
over Alpine and far eastern Tuolumne counties. Moisture with this
system is relatively low, but the track and location of the low
still support the potential for some light showers and a rumble of
thunder or two (10% probability of thunder).

Winds peak on Tuesday, and have trended a little stronger in the
forecast, with the low pressure digs further southeast into
SoCal, ushering in north to east wind gusts of 15-25 mph in the
Valley; 30-40 mph over the Sierra and the far western Sacramento
Valley and eastern foothills of the Coast Range. While not the
classic Inside Slider pattern, with a cold, dry low moving into
the Great Basin, elevated fire weather conditions will increase
Tuesday with further drying, with daytime humidity values forecast
to be in the teens for the northern Sacramento Valley; 15-25% in
the mountains.

High temperatures will increase significantly by Tuesday with
ridging building in and the low exits, with highs Monday climbing
about 10 degrees, and a further 5-10 degrees on Tuesday. Valley
highs on Tuesday will be above normal, in the low to mid 90s.
Patches of Moderate HeatRisk are evident in the Delta and
Sacramento Metro areas.

...Thursday-Saturday (10/1-10/03)... Temperatures will remain
elevated (+5 to 10 degrees above normal) as weak eastern Pacific
ridging continues to build over interior NorCal. Winds should
generally remain light and no precipitation is expected at this
time.

&&

.AVIATION...

VFR conditions prevail across interior NorCal TAF sites this
afternoon. A few passing mid-level clouds bringing ceilings down
to 10k feet through 04z Monday at Valley TAF sites. Surface winds
generally below 12 kts in Valley, gusts up to 20 kts in Delta and
mountains next 24 hours.
&&

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

$$