941
FXUS66 KSTO 081958
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1258 PM PDT Sun Jun 8 2025

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

.DISCUSSION...

.SYNOPSIS...
Underneath split flow aloft into early next week, above normal
temperatures and mountain shower and thunderstorm chances are
expected to continue. As ridging over the Pacific Northwest begins
to break down through the middle of the week, a trend toward
cooler and more seasonable weather is anticipated as breezy
onshore flow persists.

&&

.KEY MESSAGES...

* Heat Advisory in effect through 11 PM PDT Monday for portions of
  the northern Sacramento Valley and adjacent mountains/foothills.

* Today-Tuesday:

 -Warming trend into early week ahead with hottest high
  temperatures into the triple digits in the northern Sacramento
  Valley. Widespread Moderate HeatRisk across interior NorCal and
  areas of Major HeatRisk across the northern Sacramento Valley
  expected through Monday, dissipating to areas of Moderate
  HeatRisk by Tuesday.

 --Probability of Valley High Temperatures > 95F:
  ---Northern/Central Sacramento Valley: 80-100%
  ---Delta, S. Sacramento Valley, N. San Joaquin Valley: 20-50%

 --Probability of Valley High Temperatures > 100F:
  ---Northern/Central Sacramento Valley: 75-95%, Sunday-Monday

 -Periodically breezy onshore flow in the Delta and vicinity
  during the afternoons and evenings.

 -Chances for isolated afternoon/early evening showers and
  thunderstorms:
--15-30%, across Sierra/southern Cascades, Shasta County
      Mountains, northern Coastal Range, northern Sacramento
      Valley, and adjacent foothills
    --Monday: 15-30%, across Sierra/southern Cascades north of
      Interstate 80 and northern Sacramento Valley and
      surrounding terrain.
    --Tuesday: 10-20%, across Shasta County mountains

* Wednesday-Saturday:
 -Cooling trend expected through the remainder of the week. Primarily
  Minor HeatRisk as temperatures become more seasonable.
 -Onshore flow expected to persist with periods of breezy winds,
  mainly in the afternoons and evenings and strongest across the
  Delta and vicinity.
 -Some uncertainty in potential impacts into weekend from a trough
  digging southward from the Gulf of Alaska. Continuation of
  seasonable and breezy weather anticipated at the very least.

.Changes from previous forecast...
 -Scattered thunderstorm chances into the foothills possible
  today.
 -Slight thunderstorm chances across Shasta County terrain on
  Tuesday.

&&

.AVIATION...
VFR conditions expected at TAF sites next 24 hours, with
potential MVFR/IFR in isolated mountain/foothills thunderstorms
elsewhere 21z today to 04z Monday. Onshore south-southwest winds
up to 12 kts at times persist, strongest through the Delta and
vicinity with gusts 20 to 25 kts from 21z to 06z.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 11 PM PDT Monday for Northern Sacramento
Valley-Shasta Lake Area / Northern Shasta County.

&&

$$