009 

FGUS76 KSGX 212220

ESFSGX



Hydrologic Forecast for Extreme Southwestern California

National Weather Service San Diego CA

320 PM PDT Fri Aug 21 2026



...Flash Flood Potential Index for Extreme Southwestern California...



.SYNOPSIS...

Monsoonal moisture will decrease into the weekend with a slight

chance of showers and thunderstorms for the mountains and high

desert for this afternoon. The risk of flash flooding for the

mountains and Lucerne Valley for today is low with maximum

rainfall rates around 0.25 inch/hour. No flash flooding is

expected Saturday and Sunday.



$$



CAZ055-056-058-060-221315-

San Bernardino County Mountains-Riverside County Mountains-

San Diego County Mountains-Apple and Lucerne Valleys-

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, 

and Lucerne Valley

320 PM PDT Fri Aug 21 2026



.TONIGHT...Low...the risk of flash flooding is minimal. 

.SATURDAY...None...no flash flooding is expected. 

.SUNDAY...None...no flash flooding is expected. 



$$



CAZ061-062-065-221315-

Coachella Valley-San Diego County Deserts-

San Gorgonio Pass near Banning-

Including the cities of Indio, Palm Springs, Cathedral City, 

Palm Desert, Palm Desert Country, La Quinta, Coachella, 

and Borrego Springs

320 PM PDT Fri Aug 21 2026



.TONIGHT...None...no flash flooding is expected. 

.SATURDAY...None...no flash flooding is expected. 

.SUNDAY...None...no flash flooding is expected. 



$$



CAZ043-048-050-057-552-554-221315-

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

320 PM PDT Fri Aug 21 2026



.TONIGHT...None...no flash flooding is expected. 

.SATURDAY...None...no flash flooding is expected. 

.SUNDAY...None...no flash flooding is expected. 



$$