056 FXUS66 KSTO 092024 AFDSTOArea Forecast Discussion National Weather Service Sacramento CA 124 PM PDT Thu Oct 9 2025
For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing.
.SYNOPSIS... A weak system brings scattered showers and thunderstorms today through Saturday north of I-80. A colder, wet system will then bring widespread rainfall and the season`s first measurable snowfall to the mountains, though exact amounts and timing are still uncertain.
.KEY MESSAGES...
* TODAY - SUNDAY:
- A weak system begins to bring breezy winds and scattered showers today, with precip primarily in Shasta County and the southern Cascades. Potential for rain continues through Saturday afternoon with a 55 to 80% chance of 0.25 inches in the aforementioned areas over the 72 hour period.
- 10-15% chance for thunderstorms this afternoon/evening in Shasta County, and again on Saturday afternoon/evening.
- Briefly drier conditions on Sunday before the next system arrives early next week.
* MONDAY - WEDNESDAY:
- A colder, wet system arrives early next week, bringing widespread rainfall and the season`s first measurable mountain snowfall through Wednesday.
- Exact timing and amounts are still uncertain for this system, but there`s currently a 50-60% chance for an inch of rain everywhere below 5500 ft, and a 30-50% chance for 6 inches of snow or more in the Sierra above 5500 ft.
- 10-20% chance of thunderstorms Monday evening into Tuesday morning as well, as the system begins to move onshore.
.AVIATION... General VFR conditions forecasted outside of scattered MVFR/IFR conditions in the Sacramento Valley and northern San Joaquin Valley from 09Z to 17Z Friday. A weak system will bring scattered light rain and a 15-20% chance of isolated thunderstorms to Shasta County after 06Z Friday. South winds 10-15 kts with gusts 15 to 20 kts through the Delta and northern/central Sacramento Valley until 03Z Friday. South gusts up to 25 kts over the mountains through 18Z Friday.
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.STO WATCHES/WARNINGS/ADVISORIES... None.
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NWS STO Office Area Forecast Discussion