Drivers in North Texas were cautioned to be extremely careful Friday after the region was blasted with wintry precipitation and below-freezing temperatures overnight, according to the National Weather Service.

A freezing fog advisory is in effect Saturday morning for parts of North Texas, and drivers should watch out for black ice, officials said.

Black ice is a thin layer that forms on surfaces such as roads, sidewalks and driveways when temperatures are 30 degrees or lower.