014 FGUS76 KSGX 241029 ESFSGX Hydrologic Forecast for Extreme Southwestern California National Weather Service San Diego CA 329 AM PDT Mon Aug 24 2026 ...Flash Flood Potential Index for Extreme Southwestern California... .SYNOPSIS... Monsoonal moisture will increase slightly today, then decrease slightly on Tuesday with a greater decrease during the middle of the week. There is a slight chance of afternoon showers and thunderstorms through Tuesday for the mountains and deserts with a low risk of flash flooding with isolated hourly rainfall of one- half inch or less. $$ CAZ055-056-058-060-062-250230- San Bernardino County Mountains-Riverside County Mountains- San Diego County Mountains-Apple and Lucerne Valleys- San Diego County Deserts- Including the cities of Crestline, Lake Arrowhead, Big Bear City, Big Bear Lake, Running Springs, Wrightwood, Idyllwild-Pine Cove, Julian, Pine Valley, Victorville, Hesperia, Apple Valley, Lucerne Valley, and Borrego Springs 329 AM PDT Mon Aug 24 2026 .TODAY...Low...the risk of flash flooding is minimal. .TUESDAY...Low...the risk of flash flooding is minimal. $$ CAZ061-065-250230- Coachella Valley-San Gorgonio Pass near Banning- Including the cities of Indio, Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, La Quinta, and Coachella 329 AM PDT Mon Aug 24 2026 .TODAY...None...no flash flooding is expected. .TUESDAY...None...no flash flooding is expected. $$ CAZ043-048-050-057-552-554-250230- San Diego County Coastal Areas- San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Valleys-Santa Ana Mountains and Foothills- Orange County Coastal Areas-Orange County Inland Areas- Including the cities of Oceanside, Vista, Carlsbad, Encinitas, Chula Vista, National City, San Diego, Riverside, San Bernardino, Ontario, Moreno Valley, Fontana, Rancho Cucamonga, Corona, Escondido, El Cajon, San Marcos, La Mesa, Santee, Poway, Huntington Beach, Costa Mesa, Newport Beach, Laguna Beach, San Clemente, Santa Ana, Anaheim, Garden Grove, Irvine, Orange, Fullerton, and Mission Viejo 329 AM PDT Mon Aug 24 2026 .TODAY...None...no flash flooding is expected. .TUESDAY...None...no flash flooding is expected. $$ 17