Rare September thunderstorms brought heavy rain and even hail to parts of Southern California on Friday, raising fears of flooding, especially in recent fire areas.

In the Inland Empire and desert and mountain communities, most thunderstorm activity occurred in the afternoon hours.

A flash flood warning was issued for San Bernardino County until 5:30 p.m., with up to 1 inch of rain expected, according to the National Weather Service.

Areas affected by the warning include: San Bernardino, Redlands, Yucaipa, Highland, Running Springs, Highway 18 between Running Springs and Big Bear, Highway 330 between San Bernardino and Running Springs, Angelus Oaks, Highway 18 between Running Springs and Skyforest and Mountain Home Village.

Thunderstorms also occurred in the lower desert areas, especially in the Palm Springs area, east of Desert Hot Springs and south of Yucca Valley. In Redlands and Riverside, rain fell around midday.

After the recent forest fires in Southern California, concerns about mudslides are growing

Following the recent forest fires, there are also concerns about debris and mudslides.

The Los Angeles County Sheriff’s Department has listed the unincorporated communities of Mount Baldy, Wrightwood, Big Pines, Agua Dulce and Santa Maria as “potentially at-risk locations.”

The Bridge, Line and Airport fires are the three largest active wildfires in the state. Together, they have burned more than 47,700 acres and destroyed at least 234 structures, but firefighters have made good progress in battling the flames.

Meanwhile, authorities have urged residents to avoid recently burned areas as flooding of streams, roads and normally dry arroyos is expected.

“The heavy rains are likely to trigger rockfalls, mudslides and debris flows on steep terrain, particularly in and around these areas,” the NWS said.

READ MORE | Mudslide fears grow as rains hit Southern California in battle against wildfires