Vacaville, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

680
FXUS66 KSTO 112033
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
133 PM PDT Mon Aug 11 2025

.DISCUSSION...

.SYNOPSIS...
Widespread Moderate HeatRisk and local Major HeatRisk today with
triple digit highs in the Valley. Gradual cooling trend begins
Tuesday and continues into the weekend. Dry weather prevails.
&&

.KEY MESSAGES...

*Today:
 - High confidence in well above normal temperatures today as
   upper level ridging remains over the region with widespread
   Moderate HeatRisk and local Major HeatRisk across the Valley
   and foothills and into the mountains
 - Probability of high temperatures > 100F:
    -Northern Sacramento Valley: 80-100%
    -Remainder of the Valley: 35-75%

*Tuesday-Wednesday:
 - The East Pacific ridge axis aloft weakens as an upper trough
   from western Canada drops down bringing increased onshore flow,
   cooler temperatures, and higher relative humidity
 - The increased Delta breeze will give noticeable relief for the
   Delta and southern Sacramento Valley, especially by Wednesday
   morning
 - Slightly cooler but still hot temperatures are forecast for
   Tuesday, and then continued cooling will bring temperatures
   closer to seasonable numbers by Wednesday

*Thursday-Weekend:
 - Near to below average temperatures then continue later this
   week and into the weekend with rising relative humidity
 - Periodically breezy onshore flow is forecast at times,
   strongest in the Delta vicinity and over the Sierra Crest
 - Low confidence in isolated thunderstorm potential along the
   higher elevations in the mountains this weekend (up to 10-15%
   chance), dry weather elsewhere

.Changes from previous forecast...
- Mention of low isolated mountain thunderstorm potential this
  weekend

&&

.AVIATION...
VFR conditions expected to prevail next 24 hours across interior
northern California. Sustained surface winds generally 12 kts or
less at TAF sites. West-southwest wind gusts 15-25 kts through the
Delta until 15z Tuesday. Adjacent parts of the southern
Sacramento Valley will see similar winds at 15-20kts from 22z
Monday to 06z Tuesday.

&&

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

&&

$$