Roads in many parts of Co Donegal are affected.
Motorists using all routes are warned to take care – even major routes gritted overnight.
The outside lane at Drumkeen is very slippy as is the Letterkenny to Lifford Road.
Met Éireann says an overnight frost saw temperatures in some areas drop to -5C.
Many secondary routes and back roads are slippy in places.
The cold snap will be over soon, said Met Eireann.
An Atlantic front over Ireland this evening will bring rain – and some sleet – but will take temperatures back up.