909 FXUS66 KSTO 162051 AFDSTOArea Forecast Discussion National Weather Service Sacramento CA 151 PM PDT Tue Sep 16 2025
For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing.
.DISCUSSION...
.SYNOPSIS... Another dry and warm day for Wednesday with moderate heat risk and temperatures approaching 100 degrees. The heat is short lived as clouds start moving in ahead of remnants of tropical system Mario arrive later Thursday. Scattered showers and thunderstorms with minimal impact are then expected mainly Thursday night through Saturday from that weather system.
&&
.KEY MESSAGES...
* WEDNESDAY:
- Ridging aloft brings dry conditions and above normal temperatures and areas of moderate heat risk.
* THURSDAY - SATURDAY:
- Moisture from tropical system Mario still expected to move into area bringing clouds and chance of moisture to all areas. No strong forcing with the moisture so likely most activity in higher terrain but enough mmoisture for light showers or even a thunderstorm in the valley. Main time period looks to be Thursday night through Saturday.
- Elevated fire concerns are trending down but will be highest Thursday night into Friday before moisture deepens and humidities increase.
.CHANGES FROM PREVIOUS FORECAST...
- No major changes except to decrease overall extent of thunderstorms chances.
&&
.AVIATION...
VFR conditions and clear skies expected at interior northern California TAF sites next 24 hours. Surface winds generally less than 12 kts.
&&
.STO WATCHES/WARNINGS/ADVISORIES... None. &&
$$
NWS STO Office Area Forecast Discussion