120
FXUS66 KSTO 031934
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1234 PM PDT Mon Aug 3 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Heat Advisory in effect from until 10 PM tonight for the Valley,
Delta, and foothills.
- Hottest temperatures of the week are expected today, with areas
of Major HeatRisk and Widespread Moderate across the Valley &
foothills. Widespread Moderate HeatRisk continues through this
week.
- Elevated Fire Weather Conditions in the northern Sacramento
Valley and surrounding terrain, Burney Basin, and Sierra
Foothills through Monday due to hot temperatures, low
humidities, and breezy winds.
&&
.DISCUSSION...
Today...
Strong upper level ridging remains in place over interior
Northern California today resulting in widespread Valley triple
digit temperatures and the hottest temperatures of the week. Widespread
Moderate HeatRisk and areas of Major HeatRisk are expected today
as well across portions of the Valley and foothills. As a result,
a Heat Advisory is in effect until 10 PM tonight for the Valley,
Delta, and foothills. This ridge will weaken slightly tomorrow
resulting in slightly "cooler" high temperatures, however
overnight lows in the northern Sacramento Valley and foothills
will remain elevated in the mid 70s to low 80s tonight into
tomorrow.
A passing Pac NW trough will continue bring increased north to
northwest winds through the northern/central Sacramento Valley and
Shasta County through the early afternoon with gusts 15 to 25 mph
at times. This in addition to low daytime humidity values into
the lower teens and upper single digits and limited overnight
humidity recovery, will result in elevated fire weather
conditions across the northern Sacramento Valley and surrounding
terrain, Burney Basin, and Sierra foothills through today.
Additionally, north to east transport winds will bring lofted
smoke from surrounding wildfires to Shasta County, Burney Basin,
and parts of the northern Sacramento Valley late tonight into
tomorrow morning which may result in slightly hazy
conditions.
Tuesday into this Weekend...
Ensemble guidance continues to support the subtle flattening out
of the upper ridge through Wednesday which will allow for
temperatures to cool off by a few degrees Tuesday-Wednesday,
providing some limited relief and slightly cooler overnight
temperatures. Additionally, this weakening of the ridge will
enhance Delta breeze influence resulting in marginal improvements
to humidity recovery and overnight cooling mainly through the
Delta and portions of the southern Sacramento Valley.
This upper ridge then restrengthens and heights increase Thursday
through Saturday, resulting in widespread triple digit Valley
temperatures once again with limited overnight relief and a return
to widespread Moderate HeatRisk. Despite marginal humidity
recovery improvements from the Delta Breeze, low daytime humidity
and poor overnight recovery is likely to continue for much of
interior NorCal throughout the extended forecast period.
&&
.AVIATION...
VFR conditions are expected to prevail over the next 24 hours.
Winds generally remain 12 kts or less at TAF sites from Interstate
80 southward. North to northwest gusts 15 to 25 kts are expected
in the Sacramento Valley along and west of the I-5 corridor until
21Z Monday. West to southwest gusts up to 20 kts in the Delta
from 00Z through 18Z Tuesday.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 10 PM PDT this evening for Butte County
Below 1000 ft-C. San Joaquin County including Stockton-C. Solano
County including Fairfield-C. Stanislaus County including
Modesto-C. Yolo/NE Solano including Woodland-Central Colusa
County Incl. I-5-Central Glenn Co & Interstate 5-Central
Motherlode 1000-3000 ft-E. Diablo Range Above 1000 ft-Eastern
Colusa County-Eastern Glenn County-N. Motherlode 1000-3000 ft-N.
Sac Valley in Tehama County-NE San Joaquin Valley Below 1000 ft-
Sac Metro/W. El Dorado/Amador County-Sacramento County Delta-San
Joaquin County Delta-Shasta County Foothills 1000-3000 ft-Shasta
Metro-Sierra (Tehama-Plumas) 1000-3000 ft-Southern Motherlode
1000-3000 ft-Sutter/Yuba counties below 1000 ft-Tracy Triangle
Below 1000 ft-W Tehama Co Foothills 1000-3000 ft-W. Glenn/Colusa
Foothills 1000-3000 ft-W. Stanislaus County Above 1000 ft & I-5-
W. Yolo County including Capay/I-505-Yolo / Solano County Hills.
&&
$$
