Penn Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

609
FXUS66 KSTO 182009
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
109 PM PDT Sun May 18 2025
STDAFDSTO
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.


.Discussion...

.Synopsis...
Red Flag Warning continues for Valley and Delta locations below
1000 feet through 8 PM PDT Monday. Several locations in the Valley
have observed sustained north winds at 20-25 mph and gusts up to
35 mph this afternoon, along with humidity values in the upper
teens and low/mid 20s. Upper level low pressure near the Four
Corners Region is responsible for the breezy/gusty north winds and
low RH values. Dry and sunny conditions are expected to continue
through the rest of the work week.

By Wednesday, winds will calm and offshore upper level ridging is
forecast to dominate our synoptic pattern. Resulting afternoon
high temperatures will climb into the low to mid 90s with areas of
Moderate HeatRisk on Wednesday, then by Thursday and Friday a weak
shortwave will move through the PacNW and promote onshore flow to
help lower high temperatures with areas of Minor HeatRisk.

&&

.Key Messages...

* Red Flag Warning in effect from 8 am PDT Sunday through 8 pm
  PDT Monday for Valley and Delta locations below 1000 feet.

* Today and Monday:
 -Breezy/Gusty north winds across the area, with low humidity
  values across the Valley and Delta. Critical fire weather
  conditions will continue today and tomorrow.
 -High temperatures warm on Monday to upper 80s low 90s, warmest
  temperatures in the northern San Joaquin Valley and central
  Sacramento Valley.

* Tuesday - Saturday:
 -Warming trend expected early to mid week, with areas of Minor
  HeatRisk across the Valley. Moderate HeatRisk in the Valley on
  Wednesday.
 -North to east winds expected to remain diurnally breezy while
  very dry conditions prevail.
 -Elevated fire weather conditions anticipated.

.Changes from previous forecast...
 -HeatRisk levels through the week have trended down; Wednesday
  Moderate HeatRisk remains.

&&
.AVIATION...

VFR conditions expected to prevail next 24 hours. Northerly wind
gusts 15-30 kts across the Valley and Delta through 03z Wednesday.
Strongest wind gusts are expected through 00z Tuesday.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 8 PM PDT Monday for Carquinez Strait and
Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern
Sutter, and Butte County Below 1000 Ft-Northern Sacramento
Valley to Southern Tehama County Line Below 1000 Ft-Northern San
Joaquin Valley in San Joaquin and Stanislaus Counties Below 1000
ft-Southern Sacramento Valley in Yolo-Sacramento Far Western
Placer, southern Sutter and Solano County Below 1000 Ft.

&&

$$