815 FXUS66 KSGX 051107 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 407 AM PDT Sat Jul 5 2025 .SYNOPSIS... High temperatures near average with night and morning low clouds closer to the coast can be expected through Monday. High pressure over the Desert Southwest will build into the region for Tuesday into later next week, bringing hotter weather for inland areas. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Today through Monday... The upper level trough that is currently over the eastern Pacific Ocean will continue to deepen with an upper level low becoming closed at the 500 mb level by later in the day. Subsequently, the subtropical ridge over the desert southwest will begin to further amplify with the ridge axis ever so slowly retrograding westward and back towards the region. This will allow for temperatures to steadily continue to rise each day, with a much tighter contrast in temperatures from the coast to the deserts. This, along with the tightened pressure gradient from the low and the sea breeze being enhanced during the day by the thermal low establishing itself over the lower deserts, is going to allow for winds to increase out of the west and become rather gusty each afternoon, especially through the San Gorgonio Pass. The marine layer is going to be rather persistent overnight and make it into a majority of the inland valleys of Orange and San Diego counties, and a portion of the Inland Empire. Tuesday through Friday... The upper level low is going to open back up and become absorbed back into the longwave trough upstream, meanwhile the subtropical ridge is going to continue to build with an area of high pressure setting up over Arizona. This will allow for temperatures to become very hot for the deserts and inland valleys, with heat products being possible from Tuesday through Thursday under the most intense high pressure...although there is a caveat to this, and that is the increased amount of moisture for the deserts, which may help to keep temperatures just cool enough to where the HeatRisk indices do not exceed criteria. There could also be heat products needed for the IE, as temperatures will likely top out over 100F for most locations Tuesday through Thursday, with Wednesday likely being the hottest day of the week. There could be a few locations within the Coachella Valley approaching the 120F mark. The marine layer is going to continue to thin and lower throughout this period in the forecast, and there could also be some patchy fog for some of the coastal areas and out over the open waters during the overnight hours. By Friday, the ridge will begin to weaken and temperatures will drop off closer to the seasonal average for this time of year as the region becomes more influenced by the trough over the Pacific Ocean. && .AVIATION... 051000Z....Coast/Valleys...Low clouds based 900-1400 feet MSL have pushed into SD/Orange Counties about 10-15 miles inland. Vis restrictions (3-5SM) for elevated valleys (i.e. KL18). Clouds may push a little further inland through 12z, but likely staying out of the IE. Clearing of low clouds back to the coast will occur quickly Saturday morning, by 16-17Z. VFR prevails Saturday afternoon and evening, before patchier low clouds based 700-1200 ft MSL redevelop and move ashore late in the evening, likely after 06Z Sun. Slightly less inland extent than this morning. Vis restrictions for elevated coastal terrain and western valleys. VIS restrictions (2-6SM) remain possible in FU associated with fireworks through this morning morning, especially in Orange County and western IE. Mountains/Deserts...Sunny with mostly unrestricted VIS through Saturday night. && .MARINE... No hazardous marine weather conditions are expected through Wednesday. && .BEACHES... Southerly swell (190 degrees) of 3 to 4 feet at 15-17 seconds will generate elevated surf of 4-6 ft with sets to 7 ft along south facing beaches through Sunday. In addition, strong rip and longshore currents are expected at all beaches through Sunday. A Beach Hazards Statement is in effect and contains more information. Surf may remain elevated into early next week. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Sunday evening for Orange County Coastal Areas-San Diego County Coastal Areas. PZ...None. && $$ PUBLIC...Stewey AVIATION/MARINE/BEACHES...KW