Patches of dense fog and black ice are being reported on roads this morning and motorists are urged to be cautious.
In Co Tipperary heavy fog on the N8 around Cashel has made roads hazardous with similar conditions reported in Co Laois.
The N7 at Poatlaiose, Mountmellick and on to Mountrath also requires extreme care.
Visibility on the N2 between Castleblayney in Co Monaghan up to Ashbourne in Co Meath is reduced by fog while Co Monaghan back roads are also blanketed.
Roads in Co Westmeath are described as "slippery" after overnight frost and icy conditions.
Drivers are advised while main roads are salted icy back roads are not.
Dublin is mostly ice-free but heavy fog is reported in Balbriggan.
There is widespread freezing fog in Galway and Limerick. Conditions were similar In Co Limerick.
In Co Cork the N20 is enveloped in dense fog between Charleville and Cork City and extreme care is advised on this route.