Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
515 FXUS66 KSGX 020409 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 909 PM PDT Fri Aug 1 2025 .SYNOPSIS... Temperatures near average and marine layer low clouds each night and morning along the coast and in the western valleys through Tuesday. High pressure over the Desert Southwest will likely strengthen by the late next week, bringing a warming trend with temperatures 5 to 10 degrees above average away from the coast. There is the potential for monsoon moisture to return late in the week but precipitation chances remain below 10 percent. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This evening, the marine layer is about as deep as it was at this time yesterday but the low clouds seem slower to increase in coverage and advance inland. This may be due to a weaker inversion as a result of some cooling just above the inversion. From previous discussion... Our weather continues to be controlled by the dominant upper ridge currently positioned over southern Arizona and the low/trough centered over the Gulf of Alaska. As a result, the marine layer mixed out efficiently today with sunny skies extending several miles out to sea this afternoon. High temperatures today coming in right around climatological normals to 5 degrees below normal - topping out in the 80s to low 90s for most with 100-110 degrees for the deserts. As we head through the weekend and into next week, this ridge doesn`t budge much and stays relatively weak. Still, temperatures increase very gradually through Tuesday, with high temperatures by Tuesday afternoon only a couple of degrees warmer than today. The marine layer will continue to spread inland each night and retreat back to sea each day with depth varying between 700 and 1400ft. By the middle part of next week, the center of the ridge slides a bit closer to New Mexico, but also broadens and strengthens considerably, bringing more substantial warming for Wednesday and Thursday. Thursday and Friday will likely be the hottest days of the next week, with widespread moderate HeatRisk stretching towards the coasts and high HeatRisk spreading out of the deserts locally to inland valleys. High temperatures reaching or exceeding 100 degrees for inland valleys Thurs/Fri with the deserts likely exceeding 115 degrees (~90% chance). Available moisture will likely be quite below normal for early August most of next week, but recover to closer to normal by the end of the week. Still, chances for any monsoonal thunderstorms by the end of next week stay low, about 10 percent or less. && .AVIATION... 020300Z....Coasts/Western Valleys...Low clouds based 700-1200 feet MSL are slowly moving inland, reaching its full inland extent by 07Z. VIS reduced 0-5SM over higher coastal terrain and western valleys. Scatter out Saturday 15-17Z. VFR conditions Saturday afternoon. Low clouds redevelop at the coast around 04z Sun. .Inland Valleys/Mountains/Deserts...Mostly clear with VFR conditions through late Saturday. && .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...PG AVIATION/MARINE...Westerink