A flash flood warning was issued by the National Weather Service for the mountains and deserts of East County, especially Borrego Springs, as heavy rains from thunderstorms extended near Julian to Campo.
The flash flood warning was issued at 1:20 p.m. and was to remain in effect until 4:30 p.m. Sunday, the NWS said.
"We have heavy rain with some lightning developing in the Laguna and Cuyamaca mountains extending toward Campo," forecaster Brandt Maxwell said.
"The storms are capable of producing flash flooding and debris flows in the burn area of the Chariot Fire near Mount Laguna, and also near Pine Valley near Interstate 8 and along Highway 94 west of Campo," the NWS said."Those areas will be prone to flash flooding."
The NWS cautioned drivers to avoid areas "where water covers the roadway as water depth may be too great to allow cars to cross safely. Move to higher ground."
Showers and isolated thunderstorms that began today in San Diego County's mountains and deserts were expected to last through Monday night or even into Tuesday, a weather forecaster said.
Maxwell said rain "could make it into some of the inland valleys."
Monsoon conditions aren't expected to linger past Tuesday.
"After that it looks like we'll dry out," he said.