723
FXUS66 KSTO 051106
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
406 AM PDT Mon Oct 5 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 till 10 PM Wednesday for the
Sacramento Valley, Delta, northern San Joaquin Valley, and
adjacent foothills.
- Widespread Moderate HeatRisk with areas of Major HeatRisk
through Thursday for the Delta, Valley, and Foothills.
- Confidence is increasing for a cooling trend late next
weekend, with potential for unsettled weather.
&&
.UPDATE DISCUSSION...
A line of showers and thunderstorms is currently moving northward
through the northern Sacramento Valley and northeast foothills.
These are expected to shift to the north and east of the area by
around 7 am. There is a slight chance of isolated showers and
thunderstorms over the Sierra crest for the rest of the day, with
the best potential east of the crest.
.PREVIOUS DISCUSSION...
...Today through Thursday...
High pressure dominates the western United States, with a slight
weak shortwave off the CA coast. This weak wave is bringing
increased high level moisture supplying cloud cover to the
Sacramento Valley and adjacent foothills and mountains. This helps
keep temperatures slightly cooler for today. None the less,
temperatures will continue to be unseasonably hot across the
region. The heat will only increase as we move into Monday,
Tuesday, and Wednesday with highs in the upper 90s to lower 100s.
Potential is there for at or near record highs for this time of
the year. Warmest temperatures will be within the Sacramento
Valley and northern San Joaquin Valley. Overnight lows will be
warm in the mid 60s to mid 70s, with the warmest lows in the
foothills. Skies will be generally sunny Monday through Wednesday
with light and variable winds helping to keep conditions warm.
Widespread Moderate HeatRisk is expected with areas of Major
HeatRisk in the northern San Joaquin Valley, Delta, and the
foothills. Dry conditions are also expected, with relative
humidity values in the teens to lower 20s. Poor overnight
recoveries especially in the foothills area. There does exist a
slight chance (10 percent) of a stray shower or isolated storm
within the Sierra tonight into Monday as the weak wave moves
across the region. Chances are low due to the limited instability,
lift, and moisture near the surface. But non the less, the NBM
has hinted at those chances still appearing within the Sierra
overnight into Monday morning.
A Heat Advisory remains in effect through 10PM Wednesday for the
Valley, Foothills, and Delta due to the widespread Moderate
HeatRisk and Areas of Major HeatRisk. Try to limit outdoor
activities, check on neighbors, family, friends, and animals, and
stay hydrated.
...Friday and Beyond...
Temperatures start to improve on Friday, but still remain
unseasonably warm across the area. Highs are expected to be in the
low to mid 90s Friday. Confidence has increased in the high
pressure breaking down and shifting eastward Friday into Saturday.
As this happens temperatures start to return to seasonal averages
across the region over the weekend. As the high pressure breaks
down there is a chance for a trough to move through the region
bringing the potential for unsettled weather to the region.
Uncertainty is there on timing, development, and any
precipitation chances. We see uncertainty also arise with the
temperatures after the weekend as that will be dictated by the
progression of the trough, precipitation chances, and if we remain
in an active period or not.
&&
.AVIATION...
VFR conditions through the TAF period, with light winds. Clouds
will increase through the afternoon with a BKN to OVC cloud deck
through 09-12z. After 12z, we will see SKC to FEW clouds across
the area. A few gusts up to 15kts can`t be ruled out near the
delta this evening.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 10 PM PDT Wednesday 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-
SW Solano County including Vallejo-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. Shasta County 1000-3000 ft-W. Stanislaus County
Above 1000 ft & I-5-W. Yolo County including Capay/I-505-Yolo /
Solano County Hills.
&&
$$
