A National Weather Service dense fog advisory for areas within five miles of the coast is set to remain in effect until 9 a.m., about when the fog is expected to dissipate.
NWS meteorologists said flights could be affected in and out of Lindbergh Field in San Diego and Palomar Airport in Carlsbad.
The fog could also reduce visibility to a quarter-mile or less at times, and could lead to hazardous travel conditions, including on parts of Interstates 5, 8, 805, and state Route 163, according to the NWS. Drivers were advised to slow down, use their low beams and to leave distance between their vehicle and those ahead.
Forecasters said more dense fog will be possible along the coast again this evening into Saturday morning.