Big River, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

291
FXUS66 KSTO 121912
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1212 PM PDT Sun Jul 12 2026

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

.KEY MESSAGES...

 - Monsoonal moisture bring showers and thunderstorms to the
   Sierra early next week with potential for Valley rain today and
   through mid-week.

 - Warming trend on Sunday into next week with widespread
   Moderate HeatRisk by Tuesday.

 - Monsoonal moisture and thunderstorm chances return next
   weekend.

&&

.DISCUSSION...

Clouds, light rain, and virga can be seen passing over interior
NorCal today; temperatures are slightly cooler than yesterday due
to the cloud cover, though temperatures remain near normal for the
time of year. Warmer temperatures return Monday and widespread
triple digit temperatures are likely on Tuesday and Wednesday,
with the majority of the Valley covered by Moderate HeatRisk
(hottest in the northern Sacramento Valley). Relatively cool
overnight temperatures keep conditions in the Moderate range,
especially near the Delta, as daily onshore winds/Delta breeze
gust up to 15 to 25 mph each day.

Beyond the high temperatures, our biggest area of concern will be
monitoring the push of monsoonal moisture moving into our area
today and through mid-week. With that push comes chances for
showers and thunderstorm across our area each day, with Monday and
Tuesday as our widest impact days. There remains uncertainty
regarding how widespread outside of the mountains the
thunderstorms will occur, with limiting factors including lack of
available CAPE in the morning hours and antecedent cloud cover.

Best chances for thunderstorms today are south of I-80 along the
Sierra (around 10-20%), increasing to 15-30% Monday and Tuesday.
Chances on Wednesday and Thursday are more or less zero everywhere
now, though chances return with a new push of monsoonal moisture
on Friday and into next weekend. The main impacts with any
developed storm will be lightning and new fire starts, gusty
outflow winds, and brief rain showers. Overall, we are expecting
daily elevated fire weather conditions today through Tuesday with
highest impacts Monday and Tuesday. Be sure to check back in with
the forecast and have multiple ways to receive information,
especially those with mountain travel and recreation plans.

&&

.AVIATION...
General VFR conditions prevail across interior NorCal next 24
hours. Surface wind gusts from south to southwest around 10 to 20
kts in the Sacramento Valley, Delta and Sierra Crest until 03Z
Monday but lingering Delta Breezy up to 15 kts until 09Z Monday.

Mid to high level clouds continue periods of BKN to OVC
conditions around 10-25 kft with isolated showers mainly over the
foothills and Sierra and a slight chance (5-10%) of thunderstorms
over the Sierra south of I-80 from 21Z Sunday to 03Z Monday.

&&

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

&&

$$