Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
184 FXUS66 KSGX 152159 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 159 PM PST Mon Dec 15 2025 .SYNOPSIS... High pressure and weak offshore flow will continue to bring fair weather and above normal temperatures through Friday, with cooler weather this weekend. Coastal low clouds and fog will continue each night and morning, but less inland coverage Tuesday through Thursday and more coverage Friday through the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM... Low clouds and fog have cleared from all inland areas except for the beaches this afternoon. Stratus is still widespread over the marine waters, so patchy low clouds and fog are likely to move ashore fairly early today (late afternoon into the early evening), similar to yesterday. Visibilities will be quite low as the marine layer settles and moves about 10 miles inland, especially Tuesday morning, with areas of dense fog that could lead to travel difficulties. Weak offshore winds will result in some patchiness overnight, and the marine layer will back off to the beaches earlier than today, around mid-morning. Lingering foggy conditions for the beaches and parts of Orange County looks likely again through later morning Tuesday, though. Locally breezy offshore winds in the coastal foothills and south of the Cajon Pass/west of the Banning/Gorgonio Pass will continue through Tuesday morning. Peak gusts are generally 20-30 mph, with occasional/local gusts around 40 mph. Another warm day is in store for Tuesday afternoon as the east Pacific high pressure edges into the area, with high temperatures 1-5 degrees warmer than today. With persistent high pressure aloft, the marine layer will continue to be shallow and limited to coastal areas Tues-Wed. Onshore flow resumes Wednesday, which will cool things down a tad from Tuesday for most areas west of the mountains. && .LONG TERM... Temperatures continue to oscillate for the late week as conditions flip from weak onshore to weak offshore again and ridging amplifies slightly Thursday, which will be another warm day similar to Tuesday, with high temperatures as much as 10-20 degrees above average for mid December. The flow becomes onshore again Friday into the weekend as the ridge flattens out into zonal flow over most of the western U.S. This will lead to a gradual cooling trend Friday through the weekend, though temperatures will still remain above average, which seems to be the song of the season recently. Temperatures may rise again early next week as a ridge builds over a large part of the southern U.S. Towards mid to late week a trough is likely to move south down the west coast, giving us a chance for precipitation towards Christmas Eve/Christmas, though details are fuzzy this far out. && .AVIATION... 152130Z...Coast...Low clouds will linger over coastal waters this afternoon before slowly lowering and returning to coastal land areas 00-03Z Tue. Bases 200-600 ft MSL this evening should continue to lower overnight. Coverage will be patchy with only 5 to 10 miles of inland extent, but significant vis reductions are possible where low clouds and FG develop (1/2SM or less at times). Patchy FG scattering out of San Diego County coastal areas 13-15Z Tue, and Orange County coastal areas 15-17Z. Valleys/Mountains/Deserts...Clear skies and VFR conditions expected through the TAF period. && .MARINE... Areas of fog will return to coastal waters this evening and last through Tuesday morning. Intermittent visibility reductions below 1 nautical mile expected. Otherwise, no hazardous marine conditions are expected through Friday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...CSP AVIATION/MARINE...KW