607
FXUS66 KSTO 162025
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
125 PM PDT Thu Oct 16 2025


.KEY MESSAGES...

 - Dry weather with slightly below normal temperatures across the
   region today

 - Potential for patchy fog development in the southern Sacramento
   and northern San Joaquin valleys returns Friday morning

 - Slight warming and drying trend through the weekend into early
   next week as shortwave ridging moves into the area with weak
   northerly flow.

 - A weak system Sunday into early Monday has trended farther
   north, with the forecast now dry across the area

 - Low confidence in breezy north to east winds early next week
   behind the passage of this weather system

.DISCUSSION...
Today through Saturday...There is potential for patchy fog
development again Friday morning across the southern Sacramento
and northern San Joaquin valleys as a result of the recent rain,
mostly clear skies and light winds. High resolution guidance
indicates a 40-60% chance of visibilities less than a half of a
mile for the southern Sacramento Valley and Delta, a 20-30% chance
for the northern San Joaquin Valley. Weak upper level ridging
will develop and move into the region, allowing for light
northerly flow and slightly warmer and drier weather, closer to
normal for this time of year. Forecast highs in the Valley are in
the 70s to near 80 Friday and Saturday.

Sunday...Ensembles and clusters have trended a little farther
north with an upper trough as moves across the Pacific Northwest
Sunday and Sunday night. The most recent rain forecast has
trended even drier over the area and no precipitation is now expected
to extend into interior Northern California through the weekend.
high temperatures have trended warmer and look very similar to
those on Saturday.

Monday through Wednesday...Behind the passage of the trough,
there is potential for some breezy north to east winds. The
strongest winds will be mainly along and west of Interstate 5 in
the Delta, the Sacramento Valley, the adjacent Coast Range
foothills and the Sierra, where there is a 35-55% chance of wind
gusts greater than 30 mph through Monday. Little to no impacts are
expected at this time, with fire weather concerns minimal due to
recent rain and mountain snow. We will continue to monitor trends
in the pattern and pressure gradient in case the winds trend
stronger. While there is still some spread in the ensembles for
peak wind gusts, it has been narrowing, bringing increased
confidence. Much lighter northerly flow may linger into Tuesday
morning. Temperatures have trended a little higher, with Valley
highs in the mid to upper 70s each day, which is normal for this
time of year.

There is the potential for a shift back to a wet, active pattern
late next week. Stay tuned as details on timing and intensity
of this system become more clear. EK


.AVIATION...
Expect VFR conditions to prevail through 10z, with light winds
out of the north. A few gusts up to 15kts this afternoon and
evening in RBL and RDD. Overnight fog chances increase, with the
chance for visibility reductions down to a quarter mile between
10z-16z. Confidence remains low on the coverage of the fog and
location/severity. Near the end of the TAF period winds will
increase and the sun will shine allowing fog to slowly diminish.

&&

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

$$