505 FXUS66 KSGX 071632 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 932 AM PDT Mon Jul 7 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 normal for the weekend into early next week. For early this week, night and morning low clouds and fog will reach into the western valleys becoming shallower for the middle to end of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Highs today are expected to be similar to yesterday`s as an upper level low remains centered off the coast of northern California. The low will remain in place into Tuesday before moving inland through northern California Tuesday night into Wednesday. Three to five degrees of warming is expected for Tuesday with an additional few degrees of warming into Wednesday. The marine layer will still reach into the western valleys tonight into Tuesday morning. The marine layer will decrease to around 1500 feet in depth on Wednesday, keeping low clouds and fog more confined to coastal areas Wednesday and Thursday mornings. An area of high pressure aloft will strengthen over the southwestern United States and expand west across Southern California for Wednesday and Thursday. That will bring a notable increase in high temperatures, especially for the deserts. West of the mountains, highs on Wednesday and Thursday will be four to seven degrees above average with highs in the deserts 10 degrees above average. 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, areas below 5000 ft have a 90+ percent chance of exceeding 90 degrees. 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 into early next week, but it expected to weaken. The weakening of the high will result in a gradual cooling trend for Friday into early next week. For next Sunday and Monday, NBM high temperatures for the coast and valleys will be near to around five degrees below average with the deserts around five degrees above average. High temperatures for next Sunday 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. The marine layer will deepen to 1500 to 2000 feet by next Sunday and Monday with high and morning coastal low clouds extending inland to the western valleys. && .AVIATION... 071530Z....Coast..Low clouds 1200-1800 feet MSL will clear coastal airports by 17Z. Mostly clear skies thereafter, but with patchy low clouds on immediate coast. Low clouds in more patchy coverage will gradually develop after 05Z with less probability and duration around KSNA. Bases will be around 700-1100 feet MSL with vis reduced to 1-5SM in BR along inland coastal areas. Scatter out Tuesday 14- 16Z. Increasing clouds above 12000 feet Tuesday. Valleys/Mountains/Deserts...Clear with unrestricted VIS today and tonight. Increasing clouds above 12000 feet Tuesday. && .MARINE... NW wind gusts around 20 kts near San Clemente Island Tuesday afternoon and evening. Otherwise, no hazardous marine weather is expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday for Coachella Valley-San Diego County Deserts. PZ...None. && $$ PUBLIC...CO AVIATION/MARINE...MM