152
FXUS66 KSTO 011853
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
1153 AM PDT Thu Oct 1 2026
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.KEY MESSAGES...
- Heat Advisory will go into effect 11 AM Sat - 5 PM Mon (10/3
through 10/5) for portions of the Sacramento Valley, Delta,
northern San Joaquin Valley, and adjacent foothills.
- High temperatures, 10-20 degrees above normal, will lead to
widespread Moderate HeatRisk in the Delta, Valley, and
foothills Today - Tuesday, with areas of Major HeatRisk.
&&
.DISCUSSION...
...Today & Friday (10/01-10/02)... High pressure aloft will be the
headline for at least the next 7 days, with continued dry and hot
conditions expected. For today, highs will reach the low to mid
90s across most of the Valley with upper 70s to upper 80s for the
higher elevations. Weak surge of monsoonal moisture will push
through portions of the area on Friday, along with weak offshore
troughing, will help facilitate the development of scattered high
clouds tomorrow. Resulting cloud cover will help mitigate some of
the unseasonably hot temperatures, but really only lowering highs
by a degree or two. Moderate HeatRisk across the Delta and
portions of the Sacramento Valley (south of I-80) remain in the
forecast, then mostly Minor on Friday with the cloud coverage and
somewhat improved onshore flow.
...Saturday-Monday (10/03-10/05)... Latest model runs keep high
pressure firmly in control of the weather pattern as we move into
the weekend and early next week. High temperatures will continue
to climb well-above normal (10-20 degrees) for a significant
portion of the Valley, Delta, and adjacent foothills/thermal
belts. Offshore flow on Saturday and Sunday will lead to areas of
Major HeatRisk in the Delta and surrounding terrain, with
Moderate HeatRisk for the rest of the region. With unseasonably
hot temperatures, combined with limited Delta Breeze/overnight
cooling, and potential societal impacts, we have issued a Heat
Advisory for the aforementioned areas that will go into effect
10AM Saturday morning and continue through 5PM Monday. Several
large-scale activities, along with local Fall events take place
this weekend, so if you are outside remember to drink plenty of
water/stay hydrated, find shade and take breaks, and check on
those most sensitive to heat illness!
...Tuesday and beyond...Extended guidance keeps us under broad
ridging through the middle of next week, with some slight
uncertainty if mid to upper 90s will continue late next week.
Cluster analysis reveals overall agreement in at least upper level
ridging remaining in the region, however the strength and a
slight shift to zonal heights aloft appear in some cluster
members. Regardless, we expect at least slightly above normal to
above normal high temperatures to continue through at least
Wednesday of next week. Will continue to monitor
temperature/HeatRisk trends to see if the Heat Advisory needs to
be extended into Tuesday/Wednesday.
&&
.AVIATION...
VFR conditions prevail across interior NorCal next 24 hours.
Surface wind gusts generally below 12 kts across the Valley, wind
gusts up to 15 kts in the Delta through 06z Friday. Gusts up to 20
kts next 24 hours in the higher terrain.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM Saturday to 10 PM PDT Monday for 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 Motherlode 1000-3000 ft-E. Diablo Range Above 1000 ft-
Eastern Colusa County-N. Motherlode 1000-3000 ft-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-Southern Motherlode 1000-3000 ft-
Sutter/Yuba counties below 1000 ft-Tracy Triangle Below 1000 ft-
W. Stanislaus County Above 1000 ft & I-5-W. Yolo County
including Capay/I-505-Yolo / Solano County Hills.
&&
$$
