Area Forecast Discussion
Issued by NWS San Diego, CA
Issued by NWS San Diego, CA
460 FXUS66 KSGX 011549 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 849 AM PDT Fri Aug 1 2025 .SYNOPSIS... Temperatures near average and night and morning low clouds each day along the coast and western valleys through Tuesday. High pressure over the Desert Southwest may strengthen by the middle of next week, bringing a warming trend with temperatures near 5 to 10 degrees above average away from the coast. There is the potential for monsoon moisture to return late in the week, but precipitation chances remain below 10%. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Morning update... Not much change with the morning update, the forecast remains on track. This morning`s low clouds that filled in have been clearing as expected, with mostly sunny skies expected for the remainder of the day. From previous discussion... Low clouds have spread into the western valleys this morning while skies remain clear elsewhere. Clouds will clear back to the coast by late morning. Not much excitement today with high temperatures near normal and typical sea breezes in the afternoon, strongest through the passes. An upper level high centered near southern Arizona will gradually shift westward into Saturday, then slowly weaken in response to an upper level trough moving inland to the north. Overall daily temperature fluctuations will remain minimal into early next week, generally in the mid 70s in the coastal areas, mid 80s to mid 90s for inland orange county and valleys - locally into the upper 90s in the Inland Empire, upper 90s to around 100 in the high desert, and around 109-113 in the low deserts. The marine layer will be slightly more shallow with night and morning low clouds confined to the coastal areas and far western valleys. For the latter half of next week, a stronger upper level high is forecast to position itself over NM/AZ. This will bring more significant warming for Wednesday through Friday, especially for inland areas. Thursday is currently forecast to be the hottest day, when the chance of high temperatures exceeding 100 degrees is around 60% for the inland valleys of San Diego County, 70-90% in the Inland Empire, and 90-100% for much of the high desert. Chances of high temperatures exceeding 115 are around 40-70%. Global ensembles show an increase in Precipitable Water associated with the monsoon next week, though the main plume of moisture remains to our east. At this point moisture and instability look too marginal for any shower or thunderstorm threat with precipitation chances remaining below 10%. If we do get any low- level moisture surges into the lower deserts, that could impact (lower) the high temperatures, though it just end up being slightly less hot but significantly more humid. A shallow marine layer remaining in place will moderate temperatures near the coast through this period with night and morning low clouds continuing across the coastal areas. && .AVIATION... 011530Z....Coasts/Western Valleys...Low clouds with bases 800-1200 feet MSL, tops to 1700 feet, and vis 3-5SM will scatter out by 17Z. Patchy low clouds at the immediate coast thereafter. Low clouds to redevelop at the coast after 03Z and push locally inland after 07Z. Bases around 600-1000 feet MSL with vis reduced 0-5SM over higher coastal terrain and western valleys. Scatter out Saturday 15-17Z. .Inland Valleys/Mountains/Deserts...Mostly clear with VFR conditions through Saturday morning. && .MARINE... No hazardous marine conditions are expected through Tuesday. && .BEACHES... For beaches and harbors...Small water level fluctuations will continue periodically from the diminishing tsunami. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...Munyan AVIATION/MARINE...MM