Met Eireann has issued a rarely seen Status Orange fog warning for 18 counties, including Offaly.
The counties covered are Dublin, Carlow, Kildare, Kilkenny, Laois, Wexford, Wicklow, Offaly, Westmeath, Meath, Galway, Mayo, Roscommon, Clare, Cork, Limerick, Tipperary,m and Waterford.
"Mist will thicken into fog overnight and will be dense at times," Met Eireann warned.
The warning is valid from midnight until 8am on Tuesday morning, April 9.
Extreme caution is advised on all roads in the affected counties.
Subscribe or register today to discover more from DonegalLive.ie
Buy the e-paper of the Donegal Democrat, Donegal People's Press, Donegal Post and Inish Times here for instant access to Donegal's premier news titles.
Keep up with the latest news from Donegal with our daily newsletter featuring the most important stories of the day delivered to your inbox every evening at 5pm.