336
FXUS66 KSTO 131916
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1216 PM PDT Sun Sep 13 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Critical fire weather conditions through Monday late afternoon
due to gusty winds and low daytime humidity
- Red Flag Warning in place for portions of the Sacramento
Valley and adjacent foothills until 5 PM PDT Monday
- Cooler, below normal temperatures today. Warming trend Monday
onward with Valley highs in the mid 80s to low 90s.
&&
.DISCUSSION...
Today-Monday:
Clear and sunny skies are being observed today across interior
Northern California. Temperatures are trending 10 to 15 degrees
below normal today, with forecast Valley highs in the mid to low
80s and temperatures in the 60s and 70s across the foothills and
mountains.
Today into Monday, an upper low will continue to pass through the
Pacific Northwest resulting in breezy to gusty north winds
through the Sacramento Valley and downsloping winds along the
western slopes of the Sierra. North winds are just beginning to
increase through the northern Sac Valley and northern San Joaquin
Valley with gusts to 20 mph being observed as of 12PM. North
winds will continue to increase as the day goes on, peaking early
Monday morning and into midday. Maximum gusts are forecast to be
25 to 35 mph, with the strongest winds located along and west of
the Interstate 5 corridor. These drying north winds will also keep
daytime humidities in the teens to low 20s, possibly even the
single digits on Monday. As a result, periods of critical fire
weather conditions are expected and a Red Flag Warning remains in
effect until 5 PM Monday for portions of the Sacramento Valley and
adjacent foothills.
Gusty north winds will continue through the late afternoon on
Monday, before gradually weakening. Current probabilities
advertise a 30 to 40% probability of gusts greater than 35 mph.
Temperatures are also forecast to jump several degrees on Monday with
Valley locations seeing high temperatures in the mid 80s to low
90s.
Tuesday-Saturday:
Weak troughing is forecast to remain over NorCal bringing in
period of breezy onshore flow. Humidities will remain low on
Tuesday as a result of the north winds, with moderate overnight
recoveries Monday night into Tuesday, which may bring locally
elevated fire weather conditions. Seasonable temperatures will
persist through this week, with a brief cool down midweek before
warming into the weekend. Models depict an upper low dropping into
Northern California around the midweek period which may bring
chances for isolated thunderstorms around the northern fringes and
mountains of Shasta County, however current guidance keeps any
activity further north and there is still some uncertainty with
how the pattern will play out. in the meantime, be sure to follow
the forecast at weather.gov for any updates!
&&
.AVIATION...
VFR conditions prevail at TAF sites across the forecast period.
Gusty north to northwest winds through the eastern Valley, with
gusts to 15-25 kts through 06Z Monday. A second period of gusty
north winds develops after 12Z Monday and will continue through
18Z Monday. Sacramento TAF sites may see isolated gusts to 15 kts
after 16Z Monday, but otherwise winds will be 12 kts or less.
Over the mountains and foothills, downsloping gusts 15 to 20 kts are
expected through 06Z and then again after 12Z Monday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 5 PM PDT Monday for Butte County Below
1000 ft-Central Colusa County Incl. I-5-Central Glenn Co &
Interstate 5-Eastern Colusa County-Eastern Glenn County-
Glenn/Colusa Coast Range Above 3000 ft-N. Sac Valley in Tehama
County-Shasta Metro-Sierra (Tehama-Plumas) 1000-3000 ft-
Sutter/Yuba counties below 1000 ft-W. Glenn/Colusa Foothills
1000-3000 ft.
&&
$$
