Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
566 FXUS66 KSGX 091736 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 936 AM PST Tue Dec 9 2025 .SYNOPSIS... Warm and dry conditions with periods of Santa Ana winds expected this week. Above average temperatures expected into next week, with the most significant departure from normal expected today through Thursday. Mostly clear skies are expected through at least Thursday, with low clouds and fog returning to coastal areas as early as Friday or Saturday morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Highs today are expected to be around 10 degrees above average for the coast and valleys and 15 to 20 degrees above average for the valleys and mountains. A few additional degrees of warming is expected for inland areas Wednesday and Thursday, with some cooling at the coast. The surface high pressure over the Great Basin will remain in place through Friday, continuing periods of weak Santa Ana winds. Strongest winds will remain confined to coastal mountain slopes, foothills, and below passes with gusts 25 to 35 mph. The airmass getting pushed into Southern California from the Great Basin is quite dry, with minimum afternoon relative humidity for inland areas falling to 10 to 20% each afternoon through Friday, bringing periods of elevated fire weather conditions. Skies are expected to remain mostly clear through Thursday. Chances of low clouds and fog returning to the coast begin to increase Friday with higher chances over the weekend. High resolution guidance is showing the development of a coastal eddy Thursday night into Friday, which would increase the chances of low clouds and fog returning to coastal areas. The first night or two that marine layer low clouds and fog return, the fog has the potential to be dense especially as ridging aloft remains over the area into next week. Highs for the weekend into early next week will remain above average, but not quite as warm as the middle of this week. Highs along the coast through Monday will be about 5 degrees above average and 8 to 12 degrees above average for inland areas. For the early to middle part of next week there starts to become some uncertainty in the upper level pattern. By next Tuesday, 65% of ensemble clusters are showing the ridge continuing over the West Coast, with 20% showing the ridge weakening due to an incoming trough, and 15% showing the ridge present but over the Eastern Pacific. && .AVIATION... 091630Z...Beautiful clear skies with VFR conditions expected through the TAF period at all sites. Breezy winds in the foothills and locally into the adjacent valleys out of the northeast with gusts up to 25-30 kts. && .MARINE...No hazardous marine conditions are anticipated through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE...Villafane