Gardaí are urging extreme caution, particularly in rural areas away from main routes.
“We had a number of incidents throughout Donegal on Wednesday morning and the conditions are the same this morning,” said a spokesman.
“People need to drive carefully and slowly especially in rural areas where road surfaces are extremely slippy.
“Motorists should assume that no road has been treated and black ice cannot be seen making it a particular hazard.”
Donegal County Council staff worked last night to treat main routes with gritting salt.
They are back on the roads this morning.
Temperatures fell to -4C overnight in some inlands areas of Donegal. There were also some snow flurries on the hills and in some coastal areas.
Temperatures will rise later giving a bright sunny day.
Tags: