FXUS66 KSGX 271015 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 315 AM PDT Mon Oct 27 2025 .SYNOPSIS... Coastal low clouds will extend inland into the western valleys this morning. Offshore flow and strengthening high pressure aloft will bring warming through Wednesday with periods of gusty Santa Ana winds along and below the coastal slopes of the mountains for tonight into Wednesday with the stronger gusts to 35 to 45 mph. Weak onshore flow will spread cooling inland for Thursday and Friday with high temperatures for next weekend at least a few degrees warmer as high pressure aloft strengthens. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Wednesday)... The marine layer has deepened to around 2500 feet with low clouds extending inland from the inner coastal waters to the western valleys. Offshore flow will develop tonight and continue through Wednesday with strengthening high pressure aloft for Tuesday. Northeast to east winds along and below the coastal slopes of the mountains and will gust to 35 to 45 mph at times for late tonight into Wednesday. High temperatures for today will warm as much as 5 to 10 degrees for the mountains and inland valleys. For Tuesday, high temperatures for inland Orange County and portions of the valleys will warm as much as 10 to 15 degrees with another few to around 5 degrees of warming on Wednesday depending on location. High temperatures on Wednesday will be as much as 12 to 18 degrees above average for portions of the valleys and inland coastal areas. For Wednesday, high temperatures near the coast will range from the mid 70s to lower 80s to the 90s for the valleys and inland Orange County with the lower to mid 90s for the lower deserts. Widespread moderate heat risk is expected on Tuesday and Wednesday for inland Orange County and portions of the valleys. A Heat Advisory has been issued for Tuesday and Wednesday for the valleys and inland Orange County. && .LONG TERM (Thursday through Sunday)... For Thursday and Friday, high pressure aloft will weaken and lower level flow will turn onshore. This will spread cooling inland with the greatest cooling for the coast and valleys with cooling of 5 to 10 degrees for Thursday and Friday, locally 10 to 15 degrees for portions of the valleys and inland coastal areas. High temperatures on Friday will range from the lower 70s near the coast to the 80s for the Inland Empire with the lower 90s for the lower deserts. For the weekend, onshore flow will continue with strengthening of high pressure aloft over California. High temperatures will warm at least a few degrees for the weekend. High temperatures will warm from 4 to 8 degrees above average for inland areas on Friday to 8 to 12 degrees above average for inland areas on Sunday. Sunday high temperatures will range from the lower to mid 70s near the coast to the mid 80s to lower 90s for the Inland Empire with the lower to mid 90s for the lower deserts. Night and morning coastal low clouds could begin to return near the coast by Thursday morning and could initially be in the form of dense fog. The low clouds could return to the far western valleys at times for Friday through Sunday. && .AVIATION... 260930Z...Coast/Valleys...Low clouds based near 1200-1500 feet MSL with tops to 2000 feet will continue this morning. Vis 0-5SM in western valleys and on higher coastal terrain. Scatter out 16-17Z. SCT low clouds around 1000 feet MSL after 03Z near the coast, but low confidence in cigs redeveloping this evening into Tuesday. Mountains/Deserts...Clear and VFR conditions today and tonight. && .MARINE... No hazardous marine conditions are expected through Friday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from 11 AM Tuesday to 7 PM PDT Wednesday for Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Valleys. PZ...None. && $$ PUBLIC...17 AVIATION/MARINE...MM