813
FXUS66 KSTO 141815
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1115 AM PDT Mon Sep 14 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 this 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 Today
- Precipitation Chances (10-25%) Wed-Thu for Shasta County,
Coast Range, and Southern Cascades with nonzero thunderstorm
chances (5-15%)
&&
.DISCUSSION...
Today-Tuesday:
The main weather highlight this morning is ongoing gusty north
winds along the Interstate corridor around 15-30 MPH. These winds
have generally peaked this morning and will gradually weaken
through the afternoon and evening. Dry conditions are expected to
continue this afternoon with Valley afternoon humidities in the
teens. Given the combination of winds and low relative humidity,
our Red Flag Warning remains in effect for portions of the
northern & central Sacramento Valley and adjacent foothills until
5 PM this evening. Please be sure to continue fire safety
practices and outdoor burning is not recommended.
After today, an approaching upper level low from the Pacific NW
will bring a pattern change of cooler temperatures, increased
moisture, and precipitation chances midweek. Valley highs on
Tuesday will be in the upper 80s to low 90s and localized areas
of RH in the northern Sac. Valley and eastern Central Valley
foothills.
Wednesday-Saturday:
First day of cooler weather with highs in the low to mid 80s in
the Valley and upticks in humidity for several days. With this our
aforementioned low may bring chances for isolated thunderstorms
around the mountains of Shasta County and Southern Cascades,
however current guidance keeps any activity further north and
west. There is still some model uncertainty regarding exact
location and intensity but pattern recognition points to most
likely outcome of the bulk of shower/thunderstorms, if occurring,
closer to the CA coast and further north than our forecast area.
That being said, we will monitor to monitor and reevaluate any
thunderstorm/lightning fire weather threats as we get closer!
Currently, we have a 5-15% chance of thunder near the Coast Range
with an 10-25% chance of wetting rains across the Shasta County
and Southern Cascades mountains. Precipitable water forecast show
limited support for any widespread thunderstorm development at the
moment with dry forecast soundings across various sites as well,
keeping fire weather concerns as minor impacts at this time.
Beyond Thursday, high pressure begins to develop again and will
see temperatures rebound to near seasonable and dry conditions,
particularly over the northern SAc. Valley, and breezy afternoon
winds.
As always, be sure to follow the forecast at
weather.gov/sacramento for any updates!
&&
.AVIATION...
VFR conditions prevail across TAF sites and interior NorCal over
the next 24 hours. North winds in the Central Valley gradually
decrease this afternoon and become less than 12 kts after 00Z
Tuesday. Period of breezy downslope winds in the mountains and
foothills with gusts 15-20 kts from 03Z to 16Z Tuesday. Winds turn
southerly after 18Z Tuesday with gusts 15-25 kts at times.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 5 PM PDT this afternoon 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.
&&
$$
