890
FXUS66 KSTO 281918
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1218 PM PDT Mon Sep 28 2026

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


.KEY MESSAGES...

   - Elevated fire weather conditions today-Thursday AM due to
     periods of breezy north to east winds and low humidities.

   - High temperatures, 5-15 degrees above normal, will lead to
     Moderate HeatRisk in the Delta and Valley/foothills south of
     I-80 Thursday-Sunday


&&

.DISCUSSION...

...Today-Thursday AM (9/28-10/01)...

Abundant sunshine is being observed across Northern California
this afternoon via GOES satellite. High temperatures today will
feel noticeably warmer compared to yesterday, with Valley highs
in the mid to upper 80s.

Periods of breezy northerly flow will continue through the
Sacramento Valley today through Thursday AM as a 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 to the Sacramento Valley
and portions of the Sierra.

Winds peak on Tuesday, and have trended a slightly stronger in the
forecast, as the low pressure digs further southeast into
SoCal/Desert Southwest. The resultant north to east winds are
forecast to gust 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, 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. Additionally this will increase gap flow winds through
the Coast Range and the eastern slopes of the Diablo Range,
especially into Tracy. Valley winds weaken on Wednesday, but will
remain gusty over the Sierra and through gaps and canyons into
Thursday morning.

...Thursday(rest of)-Sunday (10/01-10/04)...
High temperatures will increase significantly by Wednesday/Thursday
as ridging builds overhead and the low treks further east. High
temperatures will climb 5 to 15 degrees above normal Thursday
through Sunday. As a result, Moderate HeatRisk is expected across
the northern San Joaquin, southern Sacramento Valley, the
Motherlode, and Delta. Winds will remain light, minimizing relief
from the warm temps. No precipitation is expected over the next
several days at this time.

Take extra precautions against heat-related illnesses! If you`re
spending long periods of time outside this week into the weekend,
remember to stay hydrated, wear breathable clothing, and try to
take breaks in the shade.

&&

.AVIATION...
VFR conditions prevail across interior NorCal next 24 hours.
Periods locally breezy north surface wind gusts thru 02z Tuesday
in the Valley, with gusts up to 25 kts. Mountain wind gusts
generally below 15 kts next 24 hours. &&

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

$$