Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
415 FXUS66 KSGX 281617 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 917 AM PDT Sat Jun 28 2025 .SYNOPSIS... High temperatures will warm a few to around 5 degrees this weekend with high temperatures within a few degrees of average to around 5 degrees above average. High temperatures will then cool about 5 degrees through the middle part of next week with high temperatures on Thursday around average to around 5 degrees below average for the valleys. The marine layer lowers some this weekend, but lifts again early next week, with night and morning coastal low clouds spreading into the western valleys, clearing by the mid-late mornings. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Saturday morning update... Marine layer clouds have cleared fairly quickly to the beaches this morning, with full sunshine expected Most of the forecast remains on track through the weekend into early next way. Staying on the warm side with stronger winds through inland mountain passes Sunday into Monday. Today/Saturday will be the hottest days for the coasts/valleys, while the heat stays on through Tuesday/Wednesday in the deserts. This weekend... Ridging continues to become more amplified over the inner desert southwest and this will allow for temperatures to continue to warm, especially for the deserts. There will be some gusty winds for the high deserts and low deserts prone to gusty winds during the afternoon hours today (San Gorgonio Pass with gap flow winds), although these winds should remain below criteria, and will further weaken going into Sunday. The marine layer is going to remain nearly the same as far as coverage and timing of these clouds scattering out later on this morning, which appears to be shortly after sunrise for the inland valleys, and closer to 9 to 10 AM for the coastal areas. There could be some locations along the immediate coastline which remain broken, or occasionally go broken throughout the afternoon hours. There could be some patchy fog over the waters and for locations along the coast. There could also be some of the wind- sheltered inland areas getting patchy fog as well towards the early morning hours. Temperatures will be even warmer today and tomorrow, especially for the Inland Empire (IE), with some locations near San Bernardino and Riverside possibly hitting the 100 degree mark. The marine layer should remain relatively thin and mostly confined to the coastal regions, although there will be some clouds penetrating into the IE during the overnight hours. Throughout the work week... The overall flattened ridge positioned over the western states will remain nearly stationary as an upper level trough and low associated with it becomes nearly quasi-stationary with only slight propagation towards the east, positions itself over the Pac waters just west of Pt. Conception. The amplification of the ridge and a strong areas of high pressure located over Arizona of 592 dm, along with an increase of RH given the southerly flow in the lower levels will allow for Heat Index values to approach the threshold for Heat Advisory products. Although at this time there is not enough coverage to warrant the issuance of this product, this will continue to be evaluated to look for trends and will be later determined if the lower deserts will need a Heat Advisory for Monday. This U/L low will slowly meander eastward and allow for a gradual cooldown each day, beginning Tuesday and throughout the rest of the work week. The onshore flow will be enhanced by the trough to the west, and the marine layer will also continue to ride a little and thicken up towards the end of the week. This U/L low also appears to be quite moisture-starved, although it could allow for the development of an afternoon shower or possibly a thunderstorm over the higher terrain and/or deserts by later in the week, depending on the progression of this feature. It may also allow for there to be some areas of drizzle for the coastal and inland areas as the onshore flow becomes more persistent and allows the marine layer to thicken up more. Temperatures will continue to be relatively cool, and slightly below the seasonal average for most locations going into the early part of next weekend as an overall trough remains over the region, as ensembles continue to suggest. && .AVIATION... 281600Z....Coast/Valleys...Low clouds based around 900-1300ft MSL have been rapidly clearing to the beaches this morning, with only a few patches remaining along portions of the coast. Patchy low clouds will likely linger at San Diego County beaches through the afternoon. Clouds redevelop and push inland tonight up to 5-10 miles with similar or slightly lower bases generally after 04z. .Mountains/Deserts...Clear skies with unrestricted VIS through Sunday morning. SW/W wind gusts 25-35 kts across the deserts and mountain passes in the afternoon and early evening leading to MOD UDDFS at times. Winds weaken substantially by 06z Sunday. && .MARINE... Periods of gusty northwest winds around 15 to 18 knots possible in the outer coastal waters near San Clemente Island Sunday afternoon and evening. Otherwise, no hazardous marine conditions are expected through Wednesday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Munyan AVIATION/MARINE...Munyan