696
FXUS66 KSTO 181930
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1230 PM PDT Wed Mar 18 2026

.KEY MESSAGES...

 - Dry weather with well-above normal temperatures expected
   through the week with Minor to Moderate HeatRisk; Hottest
   Thursday-Friday

 - Cooling to just above normal temperatures this weekend with
   chances for very light precipitation and continued cooling
   early next week

&&

.DISCUSSION...

...Today...
Mostly clear, dry, and hot conditions will prevail across interior
NorCal once again today. High pressure remains in control of our
upper level air pattern, and is effectively creating a heat dome
over the region, where warm/hot, stagnant air is sinking to the
surface. Light surface winds below 8mph from the north helping
air temperatures climb steadily this afternoon as well. We will
see highs approaching and breaking 90 across the Valley today,
with a few temperature records likely to be broken today.
Widespread Minor to isolated Moderate HeatRisk is in the forecast
for this afternoon, with modest overnight relief as lows will be
in the mid to upper 50s/low 60s.

...Thursday-Saturday...
Thursday into Friday will be the hottest days this week with
minor to moderate HeatRisk in the Valley and Delta and widespread
low 90s. Current forecast have a 70-95% chance of highs over 90
degrees over the Central Valley, highest over the Delta and
northern San Joaquin areas, now including Redding and portions of
northern Tehama County. The forecast high temperatures were
adjusted slightly higher compared to the base National Blend of
Models (NBM), as probabilities for 90 or higher have increased as
well as the impressive Extreme Forecast Index (EFI) signal over
the area. Overnight relief remains through the back end of the
week with overnight lows in the 50s. Temperatures cool later this
weekend but will remain above normal.

...Sunday-Tuesday...
Cooling trend to continue on Sunday, as high pressure is forecast
to move east and weaken as it approaches the Four Corners Region.
There remains some uncertainty on how far ridging translates
eastward and how much the ridge breaks down/weakens, as ensemble
members are offering mixed signals, however heights should lower
which will offer some relief to the unseasonably warm
temperatures. Latest forecast runs have also reduced precipitation
chances Tuesday and Wednesday, due to the aforementioned low
confidence on the ridge`s behavior. Best chances for precipitation
are now forecast north of Shasta Lake.

If you are outside or planning outdoor activities this week,
please remember to drink plenty of water and wear sunscreen. As
this is an anomalous heat event, individuals may not be fully
acclimated to the emerging heat. Local waterways are also running
very cold due to snowmelt.

&&

.AVIATION...

VFR conditions are expected for the next 24 hours. Surface winds
below 12 kts. Small chance (10-20%) of lower visibilities tomorrow
morning, mainly at the northern San Joaquin sites from BR
conditions reducing viz to 4SM. Best chances from around 11z
through 15z Thursday.

&&

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

&&

$$