A dense fog advisory was in effect early Tuesday for San Diego County's coastal areas, where visibility was expected to drop as low as a quarter-mile or less at times.
"A shallow moist layer, light winds and clear skies will combine to create areas of dense fog ... along the coastal strip," according to the National Weather Service, which scheduled the advisory until 9 a.m.
The fog may affect morning commuters on Interstate 5, portions of Interstate 8 and state Route 163, the weather service said.
The agency advised motorists to slow down, use their low beam headlights and leave plenty of distance between vehicles.
