175
FXUS66 KSTO 042039
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
139 PM PDT Tue Aug 4 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.

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

 &&


.DISCUSSION...

Today-Saturday...
Upper level ridging begins to flatten out today, allowing for
marginally cooler daytime highs compared to yesterday (but only
by a few degrees) and increased onshore flow through the Delta.
Widespread Moderate HeatRisk continues today and through the
remainder of the week. The aforementioned increase in onshore
flow will continue through midweek as the ridge continues to
weaken slightly. This will provide minor relief from the heat
especially during the overnight period. 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. Additionally smoke from the Gann Wildfire
located in Calaveras County will continue affecting surrounding
communities with west winds pushing near surface smoke into the
foothills and southwesterly transport winds advecting lofted smoke
northward.

This "cooling" trend is expected to be short-lived, as the EC
ensemble guidance shows the upper ridge amplifying once again
over Northern California Friday into the weekend, resulting in
another period of hot and dry conditions similar to those earlier
this week. Areas of Major HeatRisk are already creeping into the
foothills on Saturday, and this area of coverage may increase as
we approach the weekend.

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



Sunday into early next week...
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, potentially knocking some
Valley locations finally out of the triple digits.



&&


.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
Wednesday.

&&

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

$$