A status yellow fog warning is in place across parts of Munster this morning.
The alert for Cork, Limerick, Tipperary and Waterford is in place until 10am.
But pockets of Carlow and Kilkenny are understood to be just as bad.
Motorists are being advised to only use fog lights in affected areas and keep a safe distance from the vehicle in front.
Meanwhile, those of you due to use the M9 at Danesfort – you need to know that delays can be expected today.
A stop/go will be in operation as topographical surveys are being carried out on the N10 between Danesfort and its junction (9) with the motorway.