Rio Oso, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

839
FXUS66 KSTO 272049
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
149 PM PDT Tue May 27 2025

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

.Discussion...

.Synopsis...
Generally dry weather is expected to persist as a warming trend
arrives through the remainder of the week. Areas of Moderate
HeatRisk in the Valley through Thursday become widespread with
areas of Major HeatRisk in the Valley and foothills on Friday and
Saturday. Ensemble guidance indicates a weather system then
building toward interior NorCal later in the weekend, with
potential for elevated fire weather conditions and isolated
thunderstorms returning.

&&

.Key Messages...

* Heat Advisory in effect from 11 AM Friday to 11 PM Saturday for
  Valley, Delta, and foothills.

* Today - Thursday:
 -Warming trend, with areas of Moderate HeatRisk expected in the
  Valley.
 -Probability of Valley high temperatures > 95F:
  --30-70%, highest across northern/central Sacramento Valley.
 -Slight chance (10%) of isolated mountain thunderstorms today and
  Wednesday afternoon and early evening, primarily south of
  Interstate 80.

* Friday - Saturday:
 -Triple digit heat anticipated in the Valley and foothills late
  this week with near to record high temperatures possible on
  Friday.
 -Widespread Moderate HeatRisk with areas of Major HeatRisk in
  the Valley and foothills.
 -Probability of Valley high temperatures > 100F:
  --Friday: 60-95%, highest north of Interstate 80.
  --Saturday: 50-90%, highest away from Delta breeze influenced
   areas.
 -Limited overnight relief expected across the northern/central
  Sacramento and northern San Joaquin Valleys and thermal belts
  across the foothills.
 -Probability of Valley low temperatures Friday night > 65F:
  50-95%, highest north of I-80.
 -Hot temperatures along with very low humidity and periodically
  breezy winds could lead to elevated fire weather conditions.

* Sunday - Monday:
 -Cooling trend expected late weekend into early next week as a
  weather system builds into the region.
 -Sunday high temperatures: 80s to 90s, 70s at high elevations
 -Monday high temperatures: mid 70s to upper 80s, 60s to 70s at
  high elevations
 -High uncertainty in the track of the system at this time, with
  some potential for elevated fire weather conditions in periods
  of breezier winds.
 -Some isolated thunderstorm potential on Monday, best chances
  (around 10-15%) north of Interstate 80 at this time.

.Changes from previous forecast...
 -Heat Advisory in effect from 11 AM Friday to 11 PM Saturday for
  Valley, Delta, and foothills.
 -Mountain shower/thunderstorm chances over the weekend have
  diminished, with highest thunderstorm chances now on Monday.

&&

.AVIATION...
VFR conditions expected to prevail next 24 hours. Generally light
winds less than 12 kts anticipated, although southwest gusts to
20 kts possible in the Delta and vicinity through 06z Wednesday.
Increasing south to west winds gusting 15-25 kts then expected
after 18z Wednesday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM Friday to 11 PM PDT Saturday for
Carquinez Strait and Delta-Central Sacramento Valley-Motherlode-
Mountains Southwestern Shasta County to Western Colusa County-
Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-
Northern San Joaquin Valley-Shasta Lake Area / Northern Shasta
County-Southern Sacramento Valley.

&&

$$