787 FXUS66 KSGX 080957 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 257 AM PDT Tue Jul 8 2025 .SYNOPSIS... Warmer for Wednesday and Thursday with high temperatures 5 to 10 degrees above average for inland areas. Not quite as hot for Friday through early next week with the coast and valleys near to around 5 degrees below average with the deserts around 5 degrees above average. Night and morning coastal low clouds will spread into portions of the western valleys late each night. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Thursday)... A low pressure system off the northern California coast will weaken and move inland while high pressure aloft centered over Arizona and New Mexico expands across southern California. This will bring warming for today and Wednesday with not much change for Thursday. High temperatures on Wednesday and Thursday will be a few degrees above average near the coast to around 10 degrees above average for the deserts. High temperatures on Wednesday and Thursday will range from the 70s near the coast to the mid 90s to 104 for the Inland Empire with 114 to 118 for the lower deserts. The marine layer will decrease in depth to around 1500 feet deep for Wednesday and Thursday with night and morning coastal low clouds spreading into portions of the western valleys late each night. && .LONG TERM (Friday through Monday)... On Friday, high pressure aloft will weaken slightly and onshore flow will strengthen slightly with the coast and valleys around 5 degrees cooler than Thursday with the deserts a few degrees cooler with not much change for the weekend into early next week. High temperatures will be near to around 5 degrees below average for the coast and valleys with the deserts around 5 degrees above average. High temperature will range from the lower to mid 70s near the coast to the upper 80s to upper 90s for the Inland Empire with 110 to 114 for the lower deserts. Night and morning coastal low clouds will spread inland into the western valleys late each night. && .AVIATION... 080900Z....Coast...Very patchy low clouds based 1200-1500 ft MSL are up to 10 miles inland in SD County. High uncertainty whether CIGs impact KSNA and Orange County broadly (about a 40% chance), with timeframe between 09-14z. vis reduced to 1-5SM in BR along inland and higher elevation coastal areas. Scatter out Tuesday 14-16Z. Increasing upper level clouds above 12000 ft Tuesday. Even patchier low clouds with slightly lower bases to form after 06Z Wed. Valleys/Mountains/Deserts...Unrestricted VIS through Wednesday with increasing mid/high cloud coverage this morning. && .MARINE... NW wind gusts around 20 kts near San Clemente Island Tuesday and Wednesday in the afternoons and evenings. Otherwise, no hazardous marine weather is expected through Saturday. && .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. PZ...None. && $$ PUBLIC...17 AVIATION/MARINE...Westerink