A dense fog advisory was in effect early Monday for San Diego County's coastal areas, where visibility plunged to a quarter-mile or less in some parts.
The National Weather Service issued the advisory until 8 a.m., saying the fog was stretching about 10 miles inland from the coast.
"Be prepared for sudden reduced in visibility," the weather service said, adding that motorists should slow down, use their low beam headlights and leave plenty of distance between vehicles.
