FXUS66 KSTO 032140

AFDSTO



Area Forecast Discussion

National Weather Service Sacramento CA

140 PM PST Tue Feb 3 2026



For additional details on weather and expected impacts over the

next 7 days, please visit weather.gov/sto/briefing.







.KEY MESSAGES...



 - Dry weather with patchy fog in the Valley and lower foothills

   expected through the week.

 

 - Pattern change late weekend and into early next week, with

   increasing precipitation chances.



&&



.DISCUSSION...



...Today through Friday... 



Skies continue to be mostly sunny across the area, with hazy

conditions. Areas in the northern San Joaquin Valley continue to

see low stratus and patchy dense fog this afternoon. Improvements

are expected through the evening hours for the northern San

Joaquin, but it will be short lived as we expect further fog and

low stratus overnight. Temperatures are in the 60s within the

Sacramento Valley and 50s underneath the fog and low stratus.

Areas in the mountains are in the 50s. 



HREF continues to highlight dense fog overnight for areas within

the southern Sacramento Valley towards the northern San Joaquin

Valley, but highest chances remain around Stockton and Modesto.

Thus, a Dense Fog Advisory was issued for the northern San Joaquin

area from 10pm this evening through 10am tomorrow for quarter mile

visibilities or less. Improvements to the low stratus on Thursday

and Friday as probabilities for a half mile or less have gone 

down. Temperatures have also increased, with the mid 60s to lower 

70s across the area. Warmest temps in the foothills and in the 

northern Sacramento Valley. Minimum RH values Thursday and Friday 

will be in the teens for areas within the foothills and mountains,

with light and variable winds. 



...Saturday and onward... 



Dry conditions and seasonal temperatures on Saturday as the ridge

aloft starts to breakdown and shift eastward. By the end of the

weekend and into early next week we transition to more troughing

across the southwestern United States increasing our chances for

an active weather pattern. Long range guidance from the ECMWF and

GFS indicate an active week ahead, with potential for multiple

systems moving through the southwestern United States. The first

being end of the weekend and into early next week, with a

secondary system end of next week and into the following weekend.

Probabilities for the first storm have gone up in QPF with 80 

percent chance for a quarter of an inch or greater in the 

foothills and mountains, while in the Valley probabilities have 

decreased toward 20 percent. Snowfall over 6 inches is sitting 

around 40-50 percent for the mountains. 



Confidence continues to remain low at this time on rain/snow 

amounts, timing, and breakdown of the ridge. As the pattern change

develops and we move through the week we will have a better 

understanding of impacts. 



&&



.AVIATION...



VFR conditions prevail for sites within the Sacramento Valley 

this afternoon and evening, while MOD and SCK remain IFR to MVFR 

due to fog and low stratus. Skies will be mostly sunny for the 

Sacramento Valley, with light and variable winds. Improvements to 

visibility in SCK and MOD through the afternoon, but overnight we 

expected visibilities to drop once again to IFR through the end 

of the TAF period. Areas around SAC, SMF, MCC, and MHR will see 

visibility reductions down to a half mile around 10z through 16z.



&&



.STO WATCHES/WARNINGS/ADVISORIES...

Dense Fog Advisory from 10 PM this evening to 10 AM PST 

Wednesday for Northern San Joaquin Valley.



&&



$$