141
FXUS66 KSTO 052025
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
125 PM PDT Wed Aug 5 2026

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


.KEY MESSAGES...

 - Hot and dry conditions continue this week, with widespread
   Moderate HeatRisk.

 - Moderate to locally Major HeatRisk Friday through this
   weekend.

 - 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.

 &&
.DISCUSSION...Latest satellite imagery depicts the upper-level
ridge is building back in the wake of a weak shortwave trough
exiting eastward this afternoon. Onshore breezes through the
Sacramento Valley will continue to provide a minor relief from the
heat especially during the overnight period through Thursday.
Overnight low temperatures and maximum relative humidities will
remain elevated in the foothills throughout this period, with only
the Delta and Valley receiving marginal benefits from this
increased onshore influence. Outside of the Greater Sacramento
Area and Delta, daytime RHs in the Valley will remain in the upper
single digits to mid teens through Saturday.

Ensemble and deterministic models suggest moisture pushing into
the area Thursday through this weekend northward from the
southwest. This will promote an increasing PWAT values of 0.8 to
1.0 inch (125-150% above normal) Friday, then receding for the
weekend. However, no precipitation is expected for the forecast
area. Any isolated showers/thunderstorms will be mainly over/near
the easter Sierra crest on Saturday. Also, NBM probabilities for
thunderstorms 15-20% over the eastern Sierra crest on Saturday.

For the heat, the low- level airmass across NRN CA will warm
Friday and Saturday. This will result in another period of hot
and dry conditions. Overnight low temperatures will warm up into
the mid 60s to mid 70s. This combined with afternoon temperatures
from upper 90`s to low 100s will bring an increasing heat risk.
The heat will build on Friday and then peak on Saturday, with
Moderate to locally Major HeatRisk. Locally Major HeatRisk are
expected across the foothills and mountains both days.

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.

Ensembles show the upper ridge beginning to break down on Sunday
allowing for temperature to cool off slightly as offshore
troughing develops to the northwest. This offshore troughing is
forecast to deepen early next week, with potentially more
substantial cooling by Monday.


&&

.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
18Z Thursday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$