217
FXUS66 KSTO 062051
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
151 PM PDT Thu Aug 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 in effect from 10 AM Friday through 10 PM for the
   Sacramento and San Joaquin Valleys, and foothills of the Sierra.

 - Hottest temperatures are expected on Saturday, with Moderate to
   Major HeatRisk across the Valleys & foothills. HeatRisk
   receding early next week, with lingering Moderate HeatRisk
   through mid-week.

 - Elevated Fire Weather Conditions in the northern Sacramento
   Valley and surrounding terrain, Burney Basin, and Sierra
   Foothills through Sunday due to hot temperatures and low
   humidities.

 - Isolated thunderstorm (10%) chances in the Sierra Crest south
   of Highway 50 on Friday, increasing chances (15%) this weekend.
   Elsewhere, prevailing dry weather conditions expected.

 &&

.DISCUSSION...

Upper-level ridge continue to expand across the western CONUS,
while the surface high pressure strengthens. The low-level
airmass will warm Friday and Saturday leading to widespread
triple digits with very relief overnight due to high minimum
temperatures. The heat will increase on Friday and then peak on
Saturday. Moderate to Major HeatRisk is expected across the
Valleys & foothills. The heat will have impacts on anyone without
effective cooling and/or adequate hydration. While the HeatRisk
begin to recedes on Sunday as the upper ridge begins to break
down, overnight temperatures will remain in the upper 60s to mid
70s along with widespread highs in the triple digits. A Heat
Advisory is in effect from 10 AM Friday through 10 PM Sunday for
the Valleys, foothills, and the northern Sierra.

Additionally, as a result of these continued hot and dry
conditions, fire weather conditions will remain elevated through
Sunday across the northern Sacramento Valley and surrounding
terrain, the Sierra foothills, and Burney Basin.

The mid-level moisture over southern California is observed tracking
northward this afternoon. This moisture pushes will bring an
increasing PWAT values of 0.8 to 1.0 inch (125-160% above normal)
Friday and Saturday. A shallow instability and upper-level forcing
will bring isolated showers/thunderstorms (10%) chances south of
the Highway 50 over the Sierra Crest Friday afternoon and evening,
with increasing chances (15%) over the weekend. Elsewhere,
prevailing dry weather conditions are expected.

Heading to next week, temperatures cool slightly on Monday with
as an offshore troughing develops to the northwest. Onshore flow
will bring increasing humidity over the area. Prevailing elevated
fire weather conditions will continue over the Burney Basin and
northern Sierra foothills through Monday due to breezy westerly
winds combined with low humidity in the teens. The heat is
expected to gradually recede early through mid next week, with
lingering Moderate HeatRisk through Wednesday. All ensemble
cluster suggest this offshore troughing deepening mid to late next
week, with potentially more substantial cooling by mid week.

&&

.AVIATION...

VFR conditions are expected to prevail over the next 24 hours.
Winds generally remain 12 kts or less at TAF sites. West to
southwest gusts up to 25 kts in the Delta from 00Z through 15Z
Friday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 10 AM Friday to 10 PM PDT Sunday for Burney
Basin-Butte County Below 1000 ft-C. San Joaquin County including
Stockton-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-E. Shasta /S. Cascades Above 3000
ft-Eastern Colusa County-Eastern Glenn County-Glenn/Colusa Coast
Range Above 3000 ft-Lassen Volcanic NP-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-San Joaquin County
Delta-Shasta County Foothills 1000-3000 ft-Shasta Lake Area & 1-
5 1000-3000 ft-Shasta Metro-Sierra (Cal-Tuo) 3000-5000 ft-Sierra
(Sierra-Placer) Above 5000 ft-Sierra (Tehama-Plumas) 1000-3000
ft-Sierra (Tehama-Plumas) Above 3000 ft-Sierra (Yuba-Placer)
3000-5000 ft-Sierra 3000-5000 ft-Southern Motherlode 1000-3000
ft-Sutter/Yuba counties below 1000 ft-Tehama Co Coast Range
Above 3000 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. Shasta County Above 3000 ft-W. Stanislaus
County Above 1000 ft & I-5-W. Yolo County including Capay/I-505-
Yolo / Solano County Hills.

&&

$$