A late afternoon stormed wiped over San Diego County Wednesday bringing a blanket of dark clouds, spot showers and even lightning to some parts of the county.
More than an inch of rain fell in Pine Valley, and about a third of an inch had doused Alpine, Escondido and Mt. Woodson by 4:30 p.m.
The NWS reported 396 cloud-to-ground lightning strikes in the county by 6 p.m. There were 22 reported in Riverside County, one of which sparked a fire near Murrieta that had ballooned to 1,000 acres by 9 p.m. and forced evacuations.
A flash flood warning was issued following a severe thunderstorm warning Wednesday for southeast San Diego County as a storm moved through the region.
The National Weather Service in San Diego issued the flash flood warning at 3 p.m. through 4:45 p.m.
The flash flood warning spanned these areas: Alpine; Mount Laguna; Cuyamaca Rancho State Park; Lake Cuyamaca; Lake Morena; Potrero, Highway S1 between Lake Cuyamaca and Mount Laguna.
A severe thunderstorm warning was issued until 4:15 p.m. for Riverside County and north central San Diego County. The area affected included Temecula, Highway 70 between Warner Springs and Oak Grove and Highway 74 between Hemet and Mountain Center.
Rain was pouring in places like Mira Mesa, Santee, East Village and National City before the evening commute.
San Diegans may see "weird" cloud formations at the base of thunderstorms but that is normal, NBC 7's Dagmar Midcap said.
Storm Creates Strange Cloud Formations in Skies Over San Diego
"We don't have any super cells happening," Midcap said. "Those are the kind that create tornadoes. But we do have severe thunderstorms in effect. That means hail, that means downbursts, strong winds, horizontal winds, the possibility of lightening, potentially some flash flooding."
Southern California's muggy conditions are due to a blast of monsoonal moisture from the Gulf Coast. That monsoonal moisture was also bringing stormy weather to the eastern parts of the county.
The NWS said during the hours of the heat advisory, dehydration, heat cramps and heat exhaustion are possible. People are urged to drink plenty of water, to stay out of the sun and to check on others. San Diego County has dozens of "cool zones" where people can go to escape the heat.
On Thursday, expect more widespread showers, possibly stretching to the inland valleys, and an increased chance for flash flooding.