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000 FXUS66 KSTO 211810 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1110 AM PDT Tue Jul 21 2026For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing.KEY MESSAGES
- Monsoonal moisture pushing through the area today & Wednesday, mainly bringing sprinkles or a stray shower to Valley; slight chances for higher elevation thunderstorms.
- Above normal temepratures today, then seasonable temperatures the remainder of the week with primarily Minor HeatRisk into the weekend.
- Elevated fire weather conditions today & Wednesday due to dry/wet thunderstorms chances in the higher elevations.
DISCUSSION
Cloud cover is visible on GOES West Satellite imagery this late morning, with highest coverage over the Sierra and adjacent foothills. Later this afternoon, there are continued thunderstorm chances along the Sierra crest (around 20-40%, highest south of I-80) due to a continued push of monsoonal moisture through the area. While storms are expected to move eastward, any storm that develops brings the risk of lightning strikes within as well as outside the core of the storm. This means elevated fire weather conditions continue through Wednesday before thunderstorm chances finally taper off across the area. Wednesday also sees breezy onshore winds, particularly along the western edge and in the northern portion of the Sacramento Valley. While the onshore flow will also result in relatively decent daytime minimum humidities, the winds will contribute to the elevated fire weather conditions on Wednesday in the Valley.
Temperatures now look to be highest today, before mostly seasonable temperatures return for the remainder of the week and through the weekend. Today sees fairly widespread Moderate HeatRisk in the Valley, while the remainder of the week and weekend only have Minor HeatRisk now. Temperatures will still be seasonably hot, in the 90s in the Valley, though areas near the Delta will feel the typical overnight relief from the Delta breeze.
AVIATION
VFR conditions next 24 hours across interior NorCal TAF sites. SCT to BKN clouds across the Delta and Sacramento Valley areas. Surface winds below 12 knots except in Delta vicinity where gusts of 25 to 30 knots possible through the forecast period. Increasing surface winds in the Valley, gusts up to 20 to 25 kts, after 19z Wednesday. Slight thunderstorm chances in higher elevations from 20z today through 04z Wednesday.
STO WATCHES / WARNINGS / ADVISORIES
None.