Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
485 FXUS66 KSGX 241631 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 931 AM PDT Tue Jun 24 2025 .SYNOPSIS... A few degrees of warming today, with continued below average temperatures. A gradual warming trend will continue through the end of the week. The marine layer will bring night and morning low clouds to coastal areas through the rest of the week. The marine layer is expected to become shallower, with less low cloud coverage in the valleys by the end of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Widespread low cloud coverage was observed this morning, with low clouds filling in much of the coastal basin. As of 9 AM, low clouds are beginning to clear to the coast. High resolution guidance is indicating low cloud coverage at the immediate coast this afternoon will be patchy with periods of clearing. Low clouds will start to become more widespread early this evening, and are expected to reach into the valleys overnight. The marine layer is expected to remain 2000 to 2500 ft deep through Wednesday while we remain under cyclonic flow aloft as a trough moves across the West Coast. High temperatures today will be about 2 to 5 degrees warmer than yesterday. An additional 4 to 8 degrees of warming will occur on Wednesday for the mountains, deserts, and inland valleys with continued warming on Thursday. The warming trend will bring temperatures back to right around average for Thursday. An area of high pressure will build in from the southeast for the end of the week into the weekend. Current ensemble guidance is showing the ridge axis setting up mainly over the low deserts. This would bring more noticeable warming there Friday through Monday. Chances of the low deserts exceeding 110 degrees are highest on Sunday and Monday at 60 to 80 percent. There are some indications that the position of the high pressure would allow for a moisture surge from the southeast into the low deserts over the weekend or early next week. If that were to occur, that would keep high temperature readings on the lower side of guidance. For Sunday and Monday, there is a 7 degree difference between the warmest and coolest solutions with the coolest solutions staying right around 105 degrees and the warmest exceeding 110 degrees. Conditions are also expected to warm up west of the mountains, with temperatures in the valleys reaching into the 90s. Chances of the Inland Empire exceeding 100 degrees on Sunday and Monday are mostly 20 to 30 percent, locally up to 50 percent in the eastern portion of the Inland Empire. The building high pressure aloft should keep the marine layer shallower and more confined to coastal areas and locally into the western valleys. && .AVIATION... 241630....Coast/Valleys...Low clouds are in the process of clearing from the inland edges. Bases are currently around 2500 ft MSL with tops to 2900 ft MSL. Expect clearing to the coast 17Z-19Z with some patches at the beaches into the afternoon. Low clouds begin to increase in coverage around 01Z Wed, reaching coastal TAF sites 03Z- 05Z Wed with bases lowering to around 1500 ft MSL. Patchy clouds likely to reach into parts of the IE again 10-12z Wed. .Mountains/Deserts...Clear skies with unrestricted VIS through Wednesday morning. && .MARINE... No hazardous marine conditions are expected through Saturday. && .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...PG