High surf at the beaches and possible sudden thunderstorms in the mountains prompted the National Weather Service to issue weather alerts for San Diego County Thursday.
The NWS issued a Flash Flood Warning for southeastern San Diego County until 10:15 p.m. and for the northeastern region until 11:30 p.m.
The NWS said that by around 8 pm., 2.74 inches of rain had fallen over Mount Laguna in the past half hour.
Due to the heavy rainfall, Highway S2 was "very much at risk" of flooding near Agua Caliente Hot Springs and Rancho Vallecito Airport.
The NWS recommended motorists avoid evening travel along Highway S2 because flood waters can be hard to see at night.
Areas likely to experience flooding included Mount Laguna, I-8 between Pine Valley and Imperial County, State Route 78 between Highway S2 and Borrego Springs Road, Highway S2 between Shelter Valley and Canebrake, including Agua Caliente Hot Springs and Fish Creek Wash.
The NWS issued a Beach Hazards Statement through Friday evening.
Along the coastline, waves of about four to six feet could create dangerous conditions for swimmers at south-facing beaches, like in San Diego's North County.
While the statement is in effect, it is possible for rip currents to pull swimmers and surfers out to sea.
"Large breaking waves can wash people off jetties and rocks, and capsize small boats near shore," the NWS said.
NBC 7 weathercaster Llarisa Abreu said the statement may need to be extended if conditions don't die down.