948 FXUS66 KSTO 232019 AFDSTOArea Forecast Discussion National Weather Service Sacramento CA 119 PM PDT Tue Sep 23 2025
For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing.
.SYNOPSIS... Two weather systems to impact the area over the next 7 days. Confidence high in the first which will bring showers and possibly a thunderstorm or two to valley and mountains south of I-80 late Wednesday into Thursday. Second system looking more fall like but confidence lower on that system early next week. At this time overall impact from both is low.
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.KEY MESSAGES...
* WEDNESDAY - THURSDAY:
- Temperatures cool tomorrow through the next 7 days as pattern turns a bit more active.
- Weather system moves into the region from the south bringing chance for showers and thunderstorms mainly Wednesday night and lesser chance Thursday, with the highest chances along and south of I-80, including the valley from Sacramento southward.
- Confidence increasing in a more organized trough approaching the west coast early next week, most likely Monday/Tuesday. Solutions vary at this time with the traditional ECS showing pretty light accumulations. The EC AI model however much wetter but not beyond a low impact even with the heavier amounts.
.AVIATION...
VFR conditions are expected through the TAF period, with breezy northerly winds affecting RDD and RBL through this evening. Increasing winds out of the SW to S for SMF, SAC, MHR, and MCC around 09-12z at 10-15kts. Otherwise, SKC is expected through the TAF period, with increasing clouds out of the south around 17-18z as a system moves into the region. &&
.STO WATCHES/WARNINGS/ADVISORIES... None. &&
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NWS STO Office Area Forecast Discussion