Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
143 FXUS66 KSGX 220334 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 834 PM PDT Mon Jul 21 2025 .SYNOPSIS... Below average high temperatures will continue through Saturday. Night and morning coastal low clouds will reach into portions of the valleys late each night. Warming for Sunday through Tuesday of next week will bring high temperatures to around average for the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: Looking at the latest satellite imagery, low clouds have inundated nearly all of the coastal sites, and beginning to penetrate further eastward and into portions of the valleys. These clouds should continue to fill in throughout the evening into most of the Imperial Valley. There could be some areas of drizzle possible as well, as the marine layer has thickened up slightly due to troughing and a closed 500 mb low to the northwest of the region. This will also allow for the seasonably cooler temperatures to remain in place for the next couple of days until the ridge towards the east slowly begins to strengthen, with a gradual warming trend by later in the week. It does appear that some weak troughing will help to reinforce some slightly cooler temperatures again for this upcoming weekend, with conditions remaining dry through then. (Previous discussion submitted at 123 PM): Satellite imagery at 1 PM was showing low clouds lingering in Orange County with partial clearing at San Diego County beaches. The marine layer will stay a similar depth into Tuesday, with low clouds reaching well into the coastal basin overnight. Patchy drizzle is possible west of the mountains Tuesday morning, but little to no accumulation is expected. The marine layer will become shallower (2000 to 2500 ft) Wednesday through Friday. Cumulus clouds have developed over some of the mountains as of 1 PM this afternoon. High resolution models are showing a shower or two may develop over the mountains, but little to no rainfall accumulation expected. After today, dry conditions are expected through the rest of the forecast period. Through Tuesday, high temperatures for the coast and valleys remain around average near the coast to as much as 10 to 15 degrees below average for portions of the inland valleys. Through Wednesday, high temperatures for the mountains and deserts will range mostly from 5 degrees below average for the deserts to as much as 10 to 15 degrees below average for the higher elevations in the mountains. For Thursday through Saturday, not much change for the mountains and deserts with slight cooling for the coast and valleys. High pressure to the east will bring warming for most areas for Sunday through Tuesday of next week with high temperatures warming to closer to average for the middle of next week. && .AVIATION... 220300Z....Coast/Valleys...Low clouds based 1800-2200 ft MSL have pushed into coastal areas. The entire coastal basin should fill in by 07-09z. VIS down to 2-5SM possible for elevated inland valleys and foothills where clouds intersect terrain. Periodic -DZ possible, especially after 06z, with some VIS reductions. Clearing of low clouds will be slow on Tuesday, reaching the coast/beaches by 18- 19z. Low clouds push inland again after 00z Wednesday with slightly lower bases, but similar inland extent. Mountains/Deserts...VFR conditions expected through Tuesday evening. Widely scattered cumulus based 9000 ft MSL along ridgetops after 20z Tuesday. && .MARINE... Northwest winds will approach 20 kts in the vicinity of San Clemente Island each afternoon Wed-Fri. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ UPDATE...Stewey PUBLIC...CO AVIATION/MARINE...KW