Vacaville, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

693
FXUS66 KSTO 182006
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
106 PM PDT Wed Jun 18 2025

For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.

.DISCUSSION...

.SYNOPSIS...
Hottest day of the week today with widespread Moderate HeatRisk
over the Valley and adjacent foothills. Cooling trend to follow
with stronger onshore flow Thursday-Friday. Elevated fire weather
concerns today into the weekend from low humidity and gusty winds
with moderate fire weather conditions on Saturday.

&&

.KEY MESSAGES...

* Today:

 - Hottest day of the week with triple digit highs across the
   Valley and widespread Moderate HeatRisk for the Valley and
   adjacent foothills.

 -Combination of hot weather with dry conditions may bring a brief
  period of locally elevated fire weather conditions, mainly
  across the northern Sacramento and northern San Joaquin Valley.

 -Please continue to practice heat and fire safety such as ,
  avoiding activities during the heat of the day, properly
  extinguishing any campfires, and not driving over dry grass.

*Thursday-This Weekend:

 -Gradual cooling trend expected with stronger onshore flow
  Thursday-Friday. Strongest winds expected through the Delta and
  over the Sierra. South to west forecasted shifting to north to
  west winds over the weekend.

 -Elevated fire weather conditions expected across the Sacramento
  Valley late this week due a combination of low humidity and
  locally breezy winds with Friday into Sunday, particularly
  across the northern Sacramento and northern San Joaquin Valleys.

 -Min RH values in the teens to low 20s Friday - Sunday across
  the northern Sacramento Valley, Valley Foothills, and Northern
  San Joaquin areas

 -Probability of wind gusts > 30 mph:
*60-95%: Friday across the Northern/Central Sacramento Valley
             and Delta

*50-85%: Saturday across the western Sacramento Valley, Delta,
             and southwest Northern San Joaquin Valley.

 -Isolated showers over northern Shasta County and Southern
  Cascades Friday into Saturday morning but little to no impacts
  expected.

.Changes from previous forecast...
 -Winds continue to trend stronger as the anomalously low moves
  across our area Friday into the weekend

&&

.AVIATION...

VFR conditions continue at TAF sites over the next 24 hours.
Periodic gusts around 15-20 kts in the vicinity of the Delta and N
San Joaquin areas until 06z Thu with lingering gusts through the
Delta until around 12z Thu. Gusty southwest to west wind gusts
15-30 kts develop after 18z Thu; strongest through the Delta and
vicinity and over the mountains.

&&

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

&&

$$