Met Eireann has issued an immediate weather warning for fog in Donegal this Tuesday night.
Dense fog in places has been causing impaired visibility.
Road users are being advised to take extra care.
The status yellow weather alert will be in place until 11am on Wednesday morning.
The affected areas include Carlow, Kildare, Kilkenny, Laois, Longford, Offaly, Westmeath, Wexford, Cavan, Donegal, Monaghan, Munster, Connacht.
