


Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
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. && $$