661
FXUS66 KSTO 151955
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1255 PM PDT Fri Aug 15 2025

.DISCUSSION...

.SYNOPSIS...
Warmer weather today, then near to below normal temperatures
through the weekend and into next week with mainly Minor HeatRisk
and periodically breezy onshore flow. Slight chance of
thunderstorms mainly over Shasta County vicinity this weekend,
otherwise dry conditions prevail.

&&

.KEY MESSAGES...

*Today:
 - Slightly warmer today with dry conditions
 - Afternoon highs the 90s to near 100 for much of the Valley and
   foothills
 - Widespread Minor HeatRisk with localized Moderate HeatRisk

*Weekend:
 - Cool down with near to below average temperatures over the
   weekend with Minor HeatRisk and rising relative humidity
 - Periodically breezy onshore flow is forecast at times,
   strongest in the Delta vicinity and over the Sierra Crest
 - 15-35% chance of mostly wet thunderstorms in Shasta County
   (includes northern Sacramento Valley), northern Coastal Range,
   and southern Cascades, dry weather elsewhere
 - Potential for nocturnal convection Saturday night into Sunday
   morning as well mainly in Shasta County

*Next Week:
 - Below normal temperatures on Monday will gradually warm back up
   to near normal through next week as high pressure is favored
   to build back in over the Western US, centered over the Four
   Corners region
 - Widespread Moderate HeatRisk returns to the forecast late next
   week as a result of the warming trend
 - Drying trend will bring lower relative humidity to the area mid
   to late next week, around 15-20% in the afternoons

.Changes from previous forecast...
 - Added mention of the potential for nocturnal convection
  Saturday night into Sunday morning over Shasta County vicinity

&&

.AVIATION...
VFR conditions will continue for the next 24 hours across
interior NorCal. Sustained surface winds generally at or below 12
kts except in the Delta with west-southwest surface winds 12-15
kts with gusts 20-25 kts 23Z Friday - 15Z Saturday. Northerly
surface wind gusts of up to 15-20 kts in the northern Sacramento
Valley through 03Z Saturday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$