Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
242 FXUS66 KSGX 022039 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 139 PM PDT Sat Aug 2 2025 .SYNOPSIS... Near average temperatures west of the mountains this weekend, with slightly above average temperatures in the deserts. Hotter conditions expected for the middle to end of the upcoming week. 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... An elongated area of high pressure aloft will remain over Southern California this weekend. At 1 PM temperatures along the coast were in the 60s to low 70s; mid 80s to mid 90s in the valleys and High Desert; 70s to low 80s in the mountains; and 105 to 110 degrees in the low desert. Sunday is forecast to be a few degrees warmer than today. Minimal changes in temperature are expected for Monday and Tuesday. More noticeable warming is expected for Wednesday through Friday or Saturday of the upcoming week. The upper level high will shift east towards the Arizona/New Mexico border and is expected to strengthen. This will bring warming for inland areas, with both high and low temperatures expected to be above average. Thursday is currently expected to be the hottest day of the week. While there is good agreement in the guidance that conditions will warm up, there remains some uncertainty in how much warming will occur, particularly for the deserts. The eastward shift of the high may allow for some monsoonal moisture to creep into portions of the forecast area. The main impact from that potential moisture increase would be a slight decrease in air temperature. Even with a potential air temperature decrease, there wouldn`t be much relief from the heat as an increase in humidity would result in higher heat indices. There is a 70-90% chance of high temperatures of 100 or more in the interior portions of the Inland Empire and a 70-100% chance for lower elevations of the High Desert. There is a 70-90% chance of high temperatures of 115 or more across the low deserts, but a less than 10% chance of temperatures of 120 or more. Widespread moderate, to locally high HeatRisk is expected for the valleys, mountains, and High Desert Wednesday through Friday. Widespread major HeatRisk is expected in the lower desert. By Saturday, the majority of ensemble guidance indicates that the high will weaken, allowing for about 5 degrees of cooling. Only 30% of the ensemble space maintains the high`s strength and position indicating hotter conditions into Saturday. The marine layer is expected to get shallower in the Wednesday through Friday timeframe, becoming more confined to coastal areas. && .AVIATION... 022030Z....Coasts/Western Valleys...Clouds have cleared out nicely, with mostly sunny skies with VFR conditions prevailing through the day. Clouds redevelop and move inland after 03z Sunday, initially across San Diego County. CIGs returning to KSAN/KCRQ as early as 03- 04z but will likely take until around 09-10z Sunday to fill into KSNA and Orange County. Bases will be similar as to what was seen this morning, about 600-1000ft MSL, with inland extent to about 10- 15 miles. VIS restrictions 1-5SM where clouds intersect higher coastal terrain and locally within valleys. Clouds scatter back to the coasts 15-17z Sunday morning. .Inland Valleys/Mountains/Deserts...Mostly clear with VFR conditions through Sunday 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...CO AVIATION/MARINE...Munyan