Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
138 FXUS66 KSTO 312123 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 123 PM PST Sat Jan 31 2026 .KEY MESSAGES... - Dry weather with patchy fog in the Valley and lower foothills expected through Sunday. - Precipitation chances continue to trend down for Sunday into early Monday morning. - Dry weather continues next week with above-normal high temperatures and chances for AM fog. && .DISCUSSION... ...Saturday through Sunday... Ridging continues to dominate the pattern overhead today resulting in dry conditions. The potential for widespread dense fog returns tonight into tomorrow morning with current guidance indicating a 50 to 80% chance of visibilities less than 1/2 mile across the Delta, central/southern Sacramento Valley, and northern San Joaquin Valley. Highest chances for dense fog exist in the southern Sacramento and northern San Joaquin valleys. A Dense Fog Advisory is in effect from 11 PM tonight to 12 pm PST Sunday for the aforementioned areas. Be sure to slow down and use low-beam headlights if fog is encountered while driving. A weak trough will disrupt ridging aloft on Sunday bringing a nonzero chance for isolated light rain over Shasta County and the Coast Range, but precipitation chances continue to trend drier with the latest runs. Widespread fog chances return Sunday night into Monday morning. ...Monday through Friday... Ridging builds back in on Monday, with dry and warmer weather anticipated across interior NorCal along with continued chances for morning fog. North to east winds will be breezy through the northern and central Sacramento Valley and the Sierra mountains/foothills on Monday with gusts 15-25 mph at times. These winds will work against widespread dense fog development in the central Sacramento Valley, but isolated coverage is still possible in the southern Sacramento and northern San Joaquin valleys Tuesday night. Temperatures will follow a warming trend, climbing to above- normal by midweek as ridging continues to strengthen overhead. This will result in strong inversions that will keep conditions warm and dry in the foothills through midweek. Otherwise, breezy offshore flow is expected at times. Ensemble guidance highlights another shortwave trough approaching the region toward late week which is expected to bring cooler temperatures. && .AVIATION... Lingering MVFR conditions this afternoon mainly in the northern San Joaquin Valley from BR/HZ, elsewhere VFR conditions through around 03z Sunday. BR/FG to develop in the southern Sacramento Valley, Delta, and northern San Joaquin Valley resulting in IFR/LIFR conditions through around 20z Sunday. Surface winds below 12 kts across the region. && .STO WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory from 11 PM this evening to noon PST Sunday for Carquinez Strait and Delta-Central Sacramento Valley- Northern San Joaquin Valley-Southern Sacramento Valley. && $$