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.

&&



$$