FXUS66 KSGX 091821 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 1121 AM PDT Thu Jul 9 2026 .SYNOPSIS... The warming trend will continue today with high temperatures for Friday and Saturday a few degrees cooler. The flow across the area becomes southeasterly for Sunday into next week allowing for an influx of monsoonal moisture. For Sunday into the middle of next week, there will be a chance for showers and thunderstorms with the greater chances over the mountains and during the afternoon and early evening each day. Increasing humidity will result in warmer nights and higher HeatRisk by the middle of next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... ...UPDATED AVIATION DISCUSSION... .SHORT TERM (Today through Saturday)... The warming trend will continue today with high temperatures for Friday and Saturday a few degrees cooler. There will be widespread major HeatRisk for the lower deserts today with widespread moderate HeatRisk for other inland areas. High temperatures for today will be around average near the coast to 5 to 10 degrees above average for the mountains, deserts, and inland valleys. High temperatures for today will range from the 70s near the coast to the mid 90s to 104 for the Inland Empire with 113 to 117 for the lower deserts. Night and morning coastal low clouds will spread into the far western valleys at times into the weekend. && .LONG TERM (Sunday through Wednesday)... As the center of strong high pressure moves to the northeast, the flow across the area will become southeasterly allowing for an influx of monsoonal moisture for late Saturday into Sunday with growing spread by the middle of next week as to what degree that greater moisture persists. There will be chances for showers and thunderstorms beginning on Sunday with the greater chances over the mountains and during the afternoon and early evening each day. There will be warming of low temperatures with low temperatures mostly 5 to 10 degrees above average by Wednesday and Thursday of next week. For Wednesday and Thursday of next week, there could be low temperatures for the coast and valleys mostly in the upper 60s to mid 70s and in the lower deserts in the mid 80s to lower 90s. Those warming low temperatures will result in higher HeatRisk for most areas with moderate or greater HeatRisk for most areas for Wednesday of next week except at higher elevations in the mountains and near the coast. There will be moderate to major HeatRisk for the lower deserts, the valleys, and inland Orange County. && .AVIATION... 091800Z....Coast/Valleys...Low clouds have cleared inland areas and are clinging to the coast with bases around 1,200ft MSL. There is a 30-40% chance that these low clouds will stick to most coastal areas through the TAF period. Low clouds will begin their march inland after 02-03Z Friday, reaching inland 20 miles by 06-07Z. Bases will be 700-1,100ft MSL with VIS 2-6SM along elevated coastal terrain. Low clouds will start their retreat after 15Z, clearing most coastal locations by 18Z Friday. .Mountains/Deserts...VFR conditions prevail through the TAF period. && .MARINE... No hazardous marine conditions are expected through Wednesday. && .BEACHES... Astronomical high tides of 7.0-7.2 ft are forecast July 12-14. Higher than normal tides combined with a modest south swell (3 ft swell 14/15 seconds from 190 degrees) generating surf of 4-6 ft may result in areas of coastal flooding in low lying areas, boardwalks, beach parking lots, and beach adjacent streets during evening high tides. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory until 8 PM PDT Friday for Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains. Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning. PZ...None. && $$ PUBLIC...Martin AVIATION/MARINE/BEACHES...Villafane