The National Weather Service issued a dense fog warning Saturday night for most of the state.

Road visibility will be down to one one-quarter mile or less at times and may drop to near zero overnight, the weather service warned. The advisory will be in effect until 1 a.m. Sunday in southern, central, western and Down East Maine and 4 a.m. in northern Aroostook and Piscataquis counties.

Visibility will frequently be impaired and drivers are urged to use caution and leave plenty of distance with the car ahead.