@ FXUS66 KSGX 201009 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 309 AM PDT Wed May 20 2026 .SYNOPSIS... Warming will continue for the mountains and deserts through Thursday while the coast and valleys begin to cool. For Friday through Sunday, not much change in high temperatures is expected for the mountains and deserts while the coast and valley cool a few more degrees. Cooling will begin to spread inland early next week as onshore flow strengthens. Patchier night and morning low clouds near the coast will increase in coverage and inland spread for Friday into early next week with low clouds spreading into portions of the inland valleys late each night with later or more limited clearing near the coast each afternoon. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (Today through Friday)... The humidity for inland areas will once again fall to around 10 percent for the deserts for this afternoon and 10 to 15 percent for the mountains and inland valleys. High temperatures will continue to warm for inland areas today, as much as another 4 to 8 degrees for the mountains and deserts, while coastal areas cool a few degrees. High temperatures today will range from around 70 near the coast to the mid 80s to lower 90s for the Inland Empire with the lower deserts in the mid to upper 90s. For Thursday, high temperatures will warm another few degrees for the deserts while the coast and valleys cool a few to around 5 degrees. Friday high temperatures will cool a few degrees for most areas. High temperatures on Friday will range from the mid to upper 60s near the coast to the upper 70s to mid 80s for the Inland Empire with the upper 90s for the lower deserts. The most likely location for coastal low clouds this morning is over coastal areas of southern San Diego County into the adjacent western valleys. Greater coverage of low clouds is expected for tonight into Thursday morning for coastal areas with the low clouds spreading into the western valleys for Thursday night into Friday morning. && .LONG TERM (Saturday through Tuesday)... High temperatures will change little through Sunday, generally a few degrees above average for the coast and valleys and a few to around 5 degrees above average for the mountains and deserts. High temperatures for Saturday and Sunday will range from around 70 near the coast to the upper 70s to upper 80s for the Inland Empire with the lower deserts around 100. For Monday and Tuesday, a low pressure system moving into the Pacific Northwest will strengthen the onshore flow across southern California. This will spread cooling inland with high temperatures on Tuesday a few degrees below average near sea level to 5 to 10 degrees below average for the valleys and lower coastal slopes of the mountains. High temperatures on Tuesday will range from the mid to upper 60s near the coast to the 70s for the Inland Empire with the 90s for the lower deserts. Night and morning low clouds will spread inland into portions of the inland valleys late each night with slower and more limited afternoon clearing near the coast. With the stronger onshore flow early next week, southwest to west winds for the mountains and deserts will gust to 30 to 40 mph on Tuesday afternoon and evening with gusts to around 60 mph in the northern Coachella Valley below the San Gorgonio Pass. && .AVIATION... 200930Z...Coast...Areas of low clouds based around 800-1200 feet MSL will gradually develop and cover much of coastal San Diego County and southern OC this morning. Vis reduced 1-5SM over higher coastal terrain. Scatter out by 16Z. Low clouds based around 1000 feet MSL will redevelop after 06Z tonight into Thursday and cover coastal areas more uniformly. Otherwise, mostly clear and VFR conditions today and tonight. && .MARINE... No hazardous marine conditions are expected through Sunday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...17 AVIATION/MARINE...MM