555 FXUS66 KSGX 091558 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 858 AM PDT Mon Jun 9 2025 .SYNOPSIS... Shallower marine layer each morning through mid-week with well above normal temperatures for inland areas and deserts, peaking Tuesday and Wednesday. A slight cool down is expected for the end of the week before temperatures increase again for the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .UPDATE... The marine layer was sufficiently deep this morning with some locations across San Diego county experiencing light drizzle. The marine layer will slowly lower and become more shallow in the coming days as high pressure builds in. Temperatures along the coast will only see a mild warm up while areas further inland, the deserts, and Coachella Valley will be 5-10 degrees above normal through mid week. Temperatures cool ever so slightly for the end of the week before a return to warmer temperatures is expected for the weekend. && .PREVIOUS FORECAST FROM 320 AM... .SHORT TERM (Today through Wednesday)... A weak upper level low pressure system will move inland through southern California today. High pressure to the southwest will expand into southern California for Tuesday and Wednesday. A weak low pressure system moving inland to the north will strengthen the onshore flow slightly on Wednesday. High temperatures will warm for today and Tuesday, then cool slightly for Wednesday. High temperatures on Tuesday will be as much as 5 to 10 degrees above average for the mountains, inland valleys, and high desert. High temperatures on Tuesday will range from around 70 near the coast to the mid 80s to mid 90s for the Inland Empire with 105 to 110 for the lower deserts. Through Tuesday, the marine layer will decrease in depth to around 1500 feet. Night and morning coastal low clouds will spread inland into the western valleys with limited afternoon clearing near the coast. The marine layer may begin to deepen slightly on Wednesday. && .LONG TERM (Thursday through Sunday)... The low pressure system moving inland to the north may weaken the high pressure across southern California for Thursday and Friday with a slow cooling trend. The marine layer will deepen to around 2000 feet with night and morning coastal low clouds spreading farther inland into the valleys. With the cooling, high temperatures on Friday will be mostly a few to around 5 degrees above average, into the mid 80s to lower 90s for the Inland Empire with 105 to 110 for the lower deserts. For next weekend, onshore flow will begin to weaken with high pressure to the south expanding into southern California. There will be a warming trend for next weekend with high temperatures for next Sunday 5 to 10 degrees above average for inland areas. High temperatures for next Sunday for the Inland Empire will be mostly in the 90s with 108 to 112 for the lower deserts. The marine layer will become a little shallower, but with night and morning coastal low clouds still spreading inland into the western valleys. && .AVIATION... 091515Z....Coast/Valleys...Low clouds with bases around 700-1200 feet MSL with tops to 1800 feet reached into the western and southern parts of the Inland Empire. Bases will lift and clouds will clear to the coast by 18-19Z, but with only partial and/or intermittent clearing at immediate coast. Probability of BKN-OVC clouds all day today at KSAN is around 80-90%. Clouds will push inland after 01Z tonight into Tuesday, but not as far inland as this morning. Bases would be around 500-1000 feet MSL with some vis reduced over higher coastal terrain. Mountains/Deserts...Mostly clear skies and unrestricted VIS today and tonight. && .MARINE... No hazardous marine conditions are expected through Friday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Zuber AVIATION/MARINE...Small