FXUS66 KSTO 091952

AFDSTO



Area Forecast Discussion

National Weather Service Sacramento CA

1252 PM PDT Fri May 9 2025



For additional details on weather and expected impacts over the

next 7 days, please visit weather.gov/sto/briefing.



.Discussion...



.Synopsis...

Dry and seasonably warm weather continues into the weekend, as 

well above normal high temperatures peak today and Saturday. 

Widespread Minor HeatRisk and areas of Moderate HeatRisk are 

anticipated as a result. A pattern change to cooler and unsettled 

weather is expected moving into early next week. Elevated fire 

weather conditions on Sunday will then be followed by chances for 

rain/mountain snow showers and isolated thunderstorms across 

interior NorCal Monday and Tuesday.



&&



.Key Messages...



* Today - Saturday:

 -Periodic late day breezy onshore winds.

 -Dry and warm weather with temperatures 10-15 degrees above

  normal under upper level ridging, peaking today and Saturday.

 -Areas of Moderate HeatRisk across the Central Valley Today & 

  Saturday. Probability of high temperatures 90 degrees F or 

  higher: 60-90% throughout the Valley Today & Saturday.

 

* Sunday - Tuesday: 

 -A trend toward cooler and more unsettled weather is expected,

  with a weather system arriving Sunday into early next week. 

 -Gusty southerly winds Sunday, remaining breezy Monday and

  Tuesday. Probability of gusts 40 mph or higher: 40-70% northern

  and western Sacramento Valley, and northeast foothills on Sunday.

 -Elevated Fire Weather conditions Sunday as gusty winds and low

  RH overlap, particularly across the northern/central Sacramento

  Valley. 

 -Rain and mountain snow chances expected as the system moves

  through. 

 --48-Hour Probability of Rain > 0.25": 50-80% across northern

  Sacramento Valley, Sierra north of Hwy 50, and adjacent

  foothills. 5-15% remaining Valley locations, Delta, and 

  foothills.

 --Isolated Thunderstorm Probability: 15-30% Monday and Tuesday,

  highest across north/central Sacramento Valley and along higher

  terrain. 

 -- 48-Hour Probability of Snowfall > 4": 20-50% along

  Sierra/southern Cascades above 6000 feet.



* Mid to Late Next Week:

 -Progressive west-northwesterly flow aloft expected.

 -Generally dry weather, with temperatures warming to near normal. 

 

.Changes from previous forecast...

 -Elevated fire weather conditions becoming more likely Sunday

  afternoon. 

 -Slight increase in isolated thunderstorm chances on both Monday

  and Tuesday. 

 

&&



.AVIATION...

VFR conditions expected across all TAF sites in the Sacramento 

Valley next 24 hours. Diurnal surface winds less than 12 knots for

the Valley. Onshore flow in the Delta with surface winds gusting 

up to around 15 knots. In the mountains, terrain driven winds with

gusts up to 25 knots through 06z Saturday. 



&&



.STO WATCHES/WARNINGS/ADVISORIES...

None.

&&



$$