A flash flood watch remains in effect until late Monday night for San Bernardino County, according to the National Weather Service. Flash flood warnings were issued Monday afternoon for parts of Southern California as the region braced for possible thunderstorms.
The severe weather alerts were upgraded from the less-serious advisory, a flash flood watch.
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Earlier in the day, watches were issued for Los Angeles, Riverside, San Bernardino and Ventura counties. Those watches expired Monday evening.
According to the NWS alerts, scattered thunderstorms were expected in the mountains, deserts and inland valleys thanks to monsoonal moisture and daytime heating.
"We could even some of these thunderstorms drifting into the valleys of LA and Ventura County," said NBC4 meteorologist Elita Loresca.
The NWS warned residents to check later forecasts and "be prepared to take action should flash flood warnings be issued."
Monday's highs for the desert, valleys and Inland Empire were in the mid-90s, while LA and inland OC were expected to top out at 87. The high for the coastal region was 80 degrees.