255
FXUS66 KSTO 171310
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
510 AM PST Sat Jan 17 2026


.KEY MESSAGES...

 - Dense fog this morning in the Valley and Delta

 - Dry weather expected next 7 days with a return to widespread
   Valley fog/low clouds and warm/dry weather at higher
   elevations.

 - High uncertainty for very light mountain precipitation late
   next week.

&&

.UPDATE DISCUSSION...

A Dense Fog Advisory has been issued through 10 am this morning for
the southern Sacramento Valley, Delta and northern San Joaquin
Valley due to widespread dens fog developing, particularly near
the Sacramento and San Joaquin rivers and the Delta. Use caution
driving, giving yourself extra time for driving this morning. Use
low beam headlights and allow extra space between you and the
vehicle in front of you.

.PREVIOUS DISCUSSION...

...Today Through Mid-Week...
Dry weather continues across the area as ridging remains in
place, with chances for patchy to dense fog and low clouds
expected over the next several days. Lingering low clouds persist
across portions of the Delta and northern San Joaquin Valley
early this afternoon, but are expected to dissipate over the next
couple of hours. HREF guidance shows a 40 to 70 percent chance of
visibility reductions below a half mile overnight and into
Saturday morning across the Delta, portions of the central and
southern Sacramento Valley, and northern San Joaquin Valley;
highest chances over the southern Sacramento and northern San
Joaquin valleys. Valley highs will be in the low 60s to mid 70s
this afternoon, before lowering slightly over the weekend. Highest
temperatures still expected in the northern Sacramento Valley and
the foothills. Breezy winds are expected at times over the
mountains and foothills during the overnight and early morning
hours.

...Mid-Week Through Late Next Week...

Ensembles show a flattening of the ridge later next week, bringing
slightly cooler temperatures and a slight potential for very
light precipitation over the mountains. Not expecting anything
impactful as there is currently a 10-25% probability of
precipitation greater than 0.1 inches over the mountains late next
week. Temperatures are expected to cool slightly, with Valley
temperatures generally in the upper 50s to low 60s. Chances for
morning fog and low clouds continue through the period.

&&


.AVIATION...


Lingering IFR/LIFR conditions in central/southern Sacramento
Valley, Delta, and northern San Joaquin Valley this morning
through 20z. FG/BR expected to develop around 05z Saturday with
similar aerial extent to this morning. Surface winds below 12 kts
in the lower elevations, with E-NE wind gusts of 25 kts in the
Sierra and Southern Cascades.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM PST this morning for Carquinez
Strait and Delta-Northern San Joaquin Valley-Southern Sacramento
Valley.

&&

$$