The California Highway Patrol reported several road closures in the Riverside County cities of Cathedral City and Moreno Valley because of flooding and rock and mud going into lanes. Near Pine Valley in San Diego, up to 6 inches of rain ran across Highway 94.
San Bernardino County Fire officials said flash flooding temporarily stranded hikers in the mountain community of Forest Falls. A sudden downpour flooded streets in Hemet.
Flash flooding also forced the closure of several roads in Joshua Tree National Park, park officials said.
Meanwhile, valley and coastal areas around Los Angeles baked in above-normal temperatures. The mercury reached 104 in some places in the San Fernando Valley and topped at 95 in Long Beach.
In Irwindale, eight student athletes were taken to the hospital after suffering heat exhaustion at a track meet.
The National Weather Service says high pressure will continue to bring hot weather until a cooling trend arrives Monday. Monsoonal flow over the area could bring the storms back by the middle of next week.