Motorists along coastal and valley roadways were advised to use extra caution Thursday morning as dense fog blankets the area.
A National Weather Service dense fog advisory for San Diego County coastal areas and valleys is set to remain in effect until 10 a.m. Thursday.
"The marine layer will become quite shallow overnight creating areas of dense fog," according to the weather service. "The most likely areas for dense fog will be over of the coastal mesas and beaches of San Diego County and Orange County."
The fog will likely affect morning travel, and forecasters said visibility could be reduced to a quarter-mile at times. Drivers were urged to slow down, use low beams and leave plenty of distance in front of them.
Forecasters said more dense fog could roll into areas up to 10 miles inland again Thursday night into Friday morning.
