Williams, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

236
FXUS66 KSTO 072114
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
214 PM PDT Sat Jun 7 2025

.DISCUSSION...

.SYNOPSIS...
Underneath split flow aloft through the weekend and 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 from 11 AM PDT Sunday through 11 PM PDT
  Monday for portions of the northern Sacramento Valley and
  adjacent mountains/foothills.

* Today-Monday:

 -Warming trend into early next week 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 Sunday-Monday.

 --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 mountain showers
  and thunderstorms:
--Today: 15-30%, south of US 50 along the Sierra Crest
--Sunday: 15-30%, across Sierra/southern Cascades, Shasta County
      Mountains, and northern Coastal Range
    --Monday: 10-20% across Sierra/southern Cascades and Shasta
      County mountains

* Tuesday-Friday:

 -Cooling trend expected through the remainder of the week. Areas
  of Moderate HeatRisk on Tuesday dissipate to 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.

.Changes from previous forecast...
 -Heat Advisory now in effect from 11 am Sunday - 11 pm Monday for
  northern Sacramento Valley and surrounding terrain.
 -Mountain thunderstorm chances for Tuesday beginning to
  dissipate.

&&

.AVIATION...
VFR conditions continue across interior NorCal next 24 hours.
Surface winds generally below 12 kts, although gusts 20 to 25 kts
expected through Delta and vicinity 22z today through 12z Sunday.
Slight chance of isolated mountain thunderstorms from Highway 50
southward 21z-03z.

&&

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

&&

$$