963
FXUS66 KSTO 061859
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1159 AM PDT Tue Oct 6 2026

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


.KEY MESSAGES...

   - Heat Advisory now in effect till 10 PM Friday for the
     Sacramento Valley, Delta, northern San Joaquin Valley, and
     adjacent foothills.

   - Widespread Moderate HeatRisk with areas of Major HeatRisk
     through Friday for the Delta, Valley, and Foothills.

   - Confidence is increasing for a cooling trend over the
     weekend/into next week, with some potential for unsettled
     weather, and elevated fire weather conditions.

&&

.DISCUSSION...

...Today through Friday...
Mostly clear skies with some lingering haze observed on GOES-18
this morning. Very light winds with upper level ridging aloft will
help keep haze at lower levels today. High temperatures will
continue to be unseasonably hot today as well, with highs in the
mid to upper 90s with triple-digit readings expected. Widespread
Moderate HeatRisk, with areas of Major HeatRisk will continue
today through Friday, and as such the Heat Advisory will continue
through Friday at 10 PM. Upper level ridging will continue to
dominate the rest of the work week with light surface winds
providing little relief to the hot temperatures. Ensembles are
beginning to show higher confidence in a breakdown of the synoptic
pattern as early as Friday afternoon, so some relief from hot
temperatures will be arriving as we move into the weekend.

...Saturday - Monday...
As mentioned above, upper level ridging will begin to break down
as a weak offshore low develops and lowers our heights. With the
offshore low developing, a slight uptick in onshore flow will help
provide some nighttime relief to the warm temperatures, as well
as usher in cooler highs in the mid to upper 70s/low 80s across
the Valley on Saturday, with further cooling into the low to mid
70s on Sunday. Broad troughing will develop across the PacNW
Sunday, with some ensembles suggesting a pseudo inside slider
pattern to evolve. Disagreement still exists regarding strength
and location of trough, but confidence continues to increase in
the overall pattern change. Troughing may usher in some unsettled
weather in the mountains on Sunday and Monday, but PWAT values
associated with the trough will be highest to the south of the
warning area. Biggest sensible weather changes will be more
seasonable, fall- like high temperatures and a period of locally
breezy north to east winds developing behind the trough Sunday
into Monday. NBM advertises north to east wind gusts of 25-35 mph
on Sunday and Monday, strongest along and west of the I-5 corridor
and in the Burney Basin. Due to recent heat and drying of fuels,
elevated fire weather conditions are likely Sunday into Monday,
especially when the north to east winds will be at their
strongest. Will continue to monitor conditions as we move closer
to the weekend.

&&

.AVIATION...

VFR conditions prevail across interior NorCal next 24 hours, with
light surface winds generally below 12 knots. East wind gusts up
to 15 to 20 knots in the higher elevations through 14z Wednesday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 10 PM PDT Friday 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.

&&

$$