GARDAÍ and the AA have issued a fog and ice warning for Donegal roads this morning.
It follows a Met Eireann Yellow Status alert for low temperatures. The warning is in place until midday.
Forecasters are warning of more icy nights ahead this week.
Many road are treacherous this morning with council officials and gardai urging motorists to drive to suit the conditions and give extra time for journeys.
Donegal County Council gritting lorries were on all major routes from 6am, the council said.
Fog warnings are in place in several areas with Letterkenny particularly bad last night.