601
FXUS66 KSTO 211810
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1110 AM PDT Tue Jul 21 2026

For 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.

&&

$$