Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
030 FXUS66 KSGX 180933 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 233 AM PDT Sat Oct 18 2025 .SYNOPSIS... Weak offshore flow will continue Saturday and Sunday. Near to slightly above average temperatures expected through Monday, before below average conditions return for the middle of the week. Gradual warming for the end of the week, with cooler conditions possible for next weekend. Marine layer low clouds and fog will be mostly absent from the coast this weekend, likely returning Monday and becoming more widespread into the middle of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Weak high pressure aloft will set in this weekend, bringing dry conditions and near to slightly above average temperatures. Weak offshore flow will continue each morning this weekend, which will help inhibit low cloud development. Offshore winds will be slightly elevated on the coastal slopes of the mountains, locally into the foothills, with peak of the winds in the early morning hours. Northeast to east wind gusts will be 30 mph or less this morning. Wind sheltered valley locations will again experience overnight low temperatures that fall into the 40s to low 50s. Offshore winds will weaken Sunday, with slightly warmer overnight low temperatures. A closed low will linger west of Southern California this weekend, before slowly moving east Monday and Tuesday. By Wednesday, the low is expected to quickly move east across Southern California. This will bring an increase in cloud coverage and cooler conditions. Westerly winds may become elevated over the mountains, locally into the deserts. By Wednesday, highs for inland locations are expected to be 7 to 12 degrees below average, with some mountain locations seeing highs near 15 degrees below average. Rain chances associated with this system continue to look marginal. Global ensembles have shown a drying trend over the last few runs, with chances of measurable rainfall occurring currently less than 10 percent. The best chances for any accumulating rain are on the coastal mountain slopes. Areas of patchy drizzle cannot be ruled out west of the mountains on Wednesday, especially with the increase in onshore flow and rapid deepening of the marine layer. As the low continues to move east weak ridging will set up again over Southern California for Thursday and Friday. This will bring a few degrees of warming, weak offshore flow, and a shallower marine layer. For next weekend, we`re monitoring the potential for a deep trough of low pressure from the Gulf of Alaska to dig south into the US West Coast. Currently, most of the ensemble guidance keeps the low off the coast of the Pacific Northwest through next Saturday (Oct 25), which would keep us dry through then. About 20 percent of solutions trend towards a wetter outcome for Southern California on Saturday with the low slightly further south and east. Current forecast for next Saturday keeps chances of precipitation under 15 percent, temperatures below average, and has an increase in cloud coverage. && .AVIATION... 180830Z....Clear and VFR conditions through early Sunday. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .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...Munyan