FGUS76 KSGX 232209
ESFSGX

Hydrologic Forecast for Extreme Southwestern California
National Weather Service San Diego CA
309 PM PDT Sun Aug 23 2026

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

.SYNOPSIS...
This afternoon, a shower or two may briefly move north near the 
Mexico border, but no flash flooding is expected. There is a
20-35% chance of showers and thunderstorms over the mountains and
locally into the adjacent deserts on Monday afternoon. Maximum
rainfall rates are forecast to be around 0.50"/hr for a low risk
of flash flooding. Shower chances lower on Tuesday with more
isolated coverage and lower rainfall rates.

$$

CAZ055-056-058-060-062-241330-
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
309 PM PDT Sun Aug 23 2026

.TONIGHT...None...no flash flooding is expected. 
.MONDAY...Low...the risk of flash flooding is minimal. 
.TUESDAY...None...no flash flooding is expected. 

$$

CAZ043-048-050-057-061-065-552-554-241330-
San Diego County Coastal Areas-
San Bernardino and Riverside County Valleys-The Inland Empire-
San Diego County Valleys-Santa Ana Mountains and Foothills-
Coachella Valley-San Gorgonio Pass near Banning-
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, Indio, 
Palm Springs, Cathedral City, Palm Desert, Palm Desert Country, 
La Quinta, Coachella, Huntington Beach, Costa Mesa, 
Newport Beach, Laguna Beach, San Clemente, Santa Ana, Anaheim, 
Garden Grove, Irvine, Orange, Fullerton, and Mission Viejo
309 PM PDT Sun Aug 23 2026

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

$$