Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
369 FXUS66 KSGX 031554 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 854 AM PDT Sun Aug 3 2025 .SYNOPSIS... High temperatures near normal for most areas, and slightly above average temperatures in the deserts through Tuesday. Hotter Wednesday through Friday with a peak in the heat on Thursday, followed by cooling next weekend. The marine layer will be persistent each night and morning for the coast and western valleys through Tuesday, becoming shallower for the middle to end of the week. 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... .Morning Update... Low clouds will continue to fade away off the coast this morning. Though areas will be clear from the clouds today, satellite currently shows smoke aloft from the Gifford Fire located on the Ventura-San Luis Obispo County line. This will lead to some hazy skies across the region, especially areas closer to the LA metro, so haze has been added to the forecast for these areas this morning with some improvement into the afternoon. Low clouds will move back inland overnight into the morning across the western valleys and coast. Chance for triple digit heat increase to around 60-80% across southern parts of the Inland Empire from Lake Elsinore to Hemet this afternoon with 20-30% chance across the high desert. .Previous Discussion (302 AM Sunday)... More of the same this morning with low clouds having filled in along the coast and extending into the western valleys, with clear skies elsewhere. Low clouds will clear by late morning with mostly sunny skies prevailing for the remainder of the day. The upper level high currently centered near the northern Gulf of California will slowly weaken today, then shifting eastward on Monday as an upper level trough moves by to the north. Overall little temperature fluctuations for the first half of the week with highs remaining near normal for the mountains westward, and up to 5 degrees above normal in the deserts. Marine layer low clouds will continue across the coastal areas and western valleys each night and morning. Global ensembles are still in good agreement with the upper high becoming centered near AZ/NM and strengthening Wednesday and Thursday, resulting in fairly minimal spread in the temperature forecast. Thursday is still forecast to be the hottest day of the week with widespread moderate HeatRisk in the valleys, mountains, and high desert, and widespread high HeatRisk in the low deserts. There is an 80-95% chance of high temperatures of 100 or more for interior portions of the Inland Empire and an 90-100% chance in the lower elevation portions of the high desert, including Victorville. For the low deserts, there is a 70-90% chance of high temperatures of 115 or more, and a 5-10% chance of high temperatures of 120 or more. The ridge weakens for Friday through the weekend, bringing a cooling trend. Otherwise, a shallower marine layer through this period with low clouds becoming more confined to the coastal areas midweek with some deepening and more widespread cloud coverage next weekend. Only other thing to note this morning is that ensembles have trended a little lower with precipitable water this week, so what little monsoon chances we had are dwindling even further, though instability never looked great. Ensembles are looking more promising towards the middle of the month, but these extended forecasts haven`t seemed to come to fruition much this summer. && .AVIATION... 031530Z....Coasts/Western Valleys...Low clouds based 900-1300 ft MSL are quickly clearing this morning, and most areas will see mostly clear by 16Z, 17Z at latest for parts of Orange County. Low clouds redevelop this evening and begin to slowly move inland after 4/05Z. Similar to slightly lower bases and slightly less inland extent than this morning. Vis reduced to 1-5SM over higher coastal terrain and elevated western valleys. Clouds clearing again 04/15-17Z. .Inland Valleys/Mountains/Deserts...Mostly clear with VFR conditions through Monday morning. && .MARINE... No hazardous marine conditions are 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...APR/SS AVIATION/MARINE...CSP