FXUS66 KSGX 220447 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 947 PM PDT Sat Mar 21 2026 .SYNOPSIS... Minor cooling continues tomorrow, though above normal temperatures persist. Slight warming next week as weaker high pressure builds back into the region, with temperatures 10-25 degrees above average through at least Friday. Areas of low clouds and fog will spread into the coastal areas each night and morning. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Evening update... Several daily high temperatures were broken once again today, and this streak will likely continue over the next several days as well above normal temperatures persist. Thermal and Indio tied their monthly record once again with a high of 108, but fortunately that should be the last of the monthly records as the upper high weakens. High temperatures tomorrow will be a few degrees lower than today. Otherwise widespread marine layer clouds have quickly redeveloped over the California Bight today and spread into the coastal areas this evening. Pathcy dense fog is possible over the higher coastal terrain and coastal mesas late tonight into Sunday morning as the marine layer spreads several miles inland. Night and morning low clouds and fog will continue through much of the week across the coastal areas. Previous discussion... Ridging moves back over the region Monday-Tuesday, then amplifies through mid-week as it moves eastwards into the desert southwest. As a result, temperatures will increase again Monday-Wednesday by a degree or two each day, but not to the extent of this previous week. Temperatures Wednesday will be 10-25 degrees above average for this time of year. Coastal areas will remain in the mid to high 70s, with 80s to low 90s in the valleys, low to mid 90s in the IE and high desert, 70s in the mountains, and mid 90s to about 101 in the low deserts. Several daily temperature records are likely to be tied or broken over the next week for inland sites, but monthly records at least are very unlikely to be challenged. Little change day to day from mid-week to late week as high pressure remains over the area and temperatures remain well above average. A pattern shift does appear to be in our future, however, with the majority of long range models showing some form of low pressure trough near the end of the month. High uncertainty remains as there are some significant model differences, but at least some cooling is very likely. && .AVIATION... 220500Z...Low clouds based 200-600 ft MSL and FG are surging past I- 5 currently into SD County as well as coastal areas of Orange County. VIS reductions 1-3SM directly east of the I-5 corridor in SD County and east of the 73/405 corridors in Orange County. Vis below 1SM (down to 1/4SM) at times in these areas (especially elevated coastal terrain). SD Co. sites near sea level (i.e. KSAN) are less likely (30% chance) to see periods of vis below 1SM than sites up to 15 miles inland (60%) and OC coastal sites (40%). Clouds/fog scatter out 15-17z Sun, yielding to VFR conditions besides some patchy low clouds developing at the immediate coast. Low clouds based 700-1200 ft return to the coast 03-06z Mon. Elsewhere, VFR conditions expected through the period. && .MARINE...Patchy fog out over the local waters tonight. Most of the fog is elevated off the water surface and not dense, though areas of visibility under 1 nautical mile remain possible locally. Visibility will improve by mid-morning Sunday. Otherwise, no hazardous marine conditions expected through Thursday. && .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...SS AVIATION/MARINE...Westerink