Met Éireann has issued a Status Yellow Fog Warning for much of the country including Clare.
The other affected counties are Carlow, Kildare, Kilkenny, Laois, Longford, Meath, Offaly, Westmeath, Cavan, Monaghan, Limerick, Tipperary and all of Connacht.
The warning comes after the weather service failed to issue a similar alert for last night when heavy fog shrouded Clare well into this morning.
Driving conditions on the M18 in particular were reported to be treacherous however motorists received no warning about the fog.
The warning issued for this evening is set to take effect at 7.00pm but thick fog had already descended on Co Clare by 5.00pm.
Met Éireann says “fairly widespread mist and fog expected, thickening and becoming dense in places.
Potential impacts include poor visibility and hazardous travelling conditions.
The warning has been issued for the hours between 7.00pm on Monday and 10.00am on Tuesday.