Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
559 FXUS66 KSGX 090459 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 859 PM PST Mon Dec 8 2025 .SYNOPSIS... Warm and dry conditions with periods of Santa Ana winds expected this week. The peak of the heat is expected to be Tuesday and Wednesday. Mostly clear skies will prevail through Friday, with low clouds and fog returning to coastal areas as early as Saturday morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Another evening of weak to moderate offshore flow has resulted in our currently completely clear skies. Winds are fairly weak through most of the region except for the usual offshore-wind- prone areas in the coastal foothills and south/west of the Cajon and Banning passes. Peak east/northeast wind gusts in these areas have generally been in the 20-30 mph range this evening with a few stations reporting gusts up to about 45 mph. Gusty winds will continue in these areas overnight. Clear skies coupled with the dry airmass will lead to efficient cooling tonight, and morning low temperatures will be similar to cooler than this morning outside of the wind corridors. Meanwhile, afternoon high temperatures Tuesday will be even warmer than today, mostly for the coastal/valley areas, with temperatures even along the immediate coast in the mid/high 70s or low 80s, and 80-87 degrees in the valleys. .PREVIOUS DISCUSSION...144 PM PST Mon Dec 8 2025... Peak wind gusts so far today have mostly been 40-45 mph. The only exceptions have been at Lytle Creek Ridge, which gusted to 47 mph and Devil Canyon which gusted to 46 mph. A peak wind gust summary has been headlined on our weather.gov/sandiego homepage. The surface high pressure over the Great Basin will remain in place through Friday, continuing periods of weak to locally moderate Santa Ana winds. Strongest winds will remain confined to coastal mountain slopes, foothills, and below passes into Tuesday morning with gusts 25-45 mph. Weaker winds are expected on Wednesday and Thursday with a bump up in winds possible Friday, although those winds have begun to trend weaker. The airmass getting pushed into Southern California from the Great Basin will be 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. An upper level ridge over the East Pacific will remain over the US West Coast, bringing an increase in high temperatures. High temperatures on Tuesday will be 15 to 20 degrees above average. Widespread highs in the low to mid 80s are forecast across the inland coastal areas into the valleys as well as the low deserts. Weaker Santa Ana winds and a weakening in the upper level ridge will allow for minor cooling for the coast on Wednesday with further cooling into the valleys on Thursday but highs will remain 10 to 20 degrees above average. Nights and mornings will remain cool, especially in the wind-sheltered areas, minimizing any heat impacts. Further cooling is expected into the weekend as weak onshore flow returns, but temperatures will continue to run above average. Low clouds and fog are not expected to impact land areas through much of this week due to persistent offshore flow. The pressure gradient will switch onshore this weekend with chances of low clouds and fog developing at the coast and western valleys as early as Saturday. && .AVIATION... 090330Z...Clear and VFR conditions will prevail through Tuesday evening. Northeast winds gusting 25-35 kts along coastal slopes, into adjacent foothills and locally into the valleys. Pockets of LLWS through 12Z, including vcty KSNA. && .MARINE... 30-40% chance for patchy fog development over the marine waters tonight. Otherwise, no hazardous marine conditions are anticipated through Saturday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CSP AVIATION/MARINE...KW