682 FXUS66 KSGX 082026 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 126 PM PDT Tue Jul 8 2025 .SYNOPSIS... Warming conditions through the middle of the week, with the hottest days expected to be Wednesday and Thursday for inland locations. Conditions will return to near average west of the mountains for the weekend into early next week, with above average temperatures remaining in the deserts. The marine layer will become shallower for the middle of the week, mainly impacting coastal areas, before deepening again over the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... An upper level low centered off the coast of northern California will weaken and move inland tonight into Wednesday morning while high pressure aloft centered over Arizona and New Mexico expands across southern California. This will bring additional warming for Wednesday with not much change for Thursday. The marine layer will become shallower and patchy Wednesday and Thursday, keeping low clouds and fog that develop more confined to coastal areas. With the upper level high expanding west across Southern California Wednesday and Thursday, above average temperatures are expected for inland locations. Highs on Wednesday and Thursday are expected to be 5 to 10 degrees above average for inland locations. High temperatures Wednesday and Thursday will range from the 70s near the coast; the upper 90s to 104 for the Inland Empire; and 114 to 118 for the lower deserts. In the mountains below 5000 ft, highs are expected to be in the mid-80 to upper 90s. Widespread moderate HeatRisk is expected for the valleys and mountains, with widespread major HeatRisk in the low deserts. Make sure you`re staying hydrated, seeking shade, and avoiding strenuous activity during the hottest parts of the day if possible. High pressure aloft will remain over Southern California Friday into early next week, but will weaken slightly. The weakening of the high aloft will result in highs on Friday 3 to 5 degrees cooler than Thursday across the area, with not much change into the weekend. NBM high temperatures for the coast and valleys are forecast to be up to 5 degrees below average with the deserts around 5 degrees above average. The marine layer will deepen Sunday through Tuesday with night and morning coastal low clouds extending inland to the western valleys. && .AVIATION... 082030Z....Coast...SCT high clouds above 15000 feet MSL. Patchy low clouds to develop after 06Z with bases 700-1000 feet MSL most likely vcnty KSAN. Scatter out of any cigs by 16Z. Valleys/Mountains/Deserts...VFR conditions with SCT-BKN high clouds above 15000 feet MSL, thinning Wednesday. && .MARINE... Northwest wind gusts around 20 kts near San Clemente Island today and Wednesday in the afternoons and evenings. Otherwise, no hazardous marine weather is expected through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from 10 AM Wednesday to 8 PM PDT Thursday for Riverside County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains- San Diego County Valleys. Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE...MM