Met Éireann says temperatures will rise over the next few hours.
Road users are being warned of icy conditions across the city and county this morning.
Gardaí say Cobh is one of the worst affected areas in the county with black ice on back roads around the town.
The road between Leamlara and Watergrasshill is particularly icy while there's been collisions on the N22 Ballincollig Bypass and on the N71 between Innishannon and Bandon which are causing traffic delays.
Speaking to RedFM News, Brandon Creagh from Met Éireann says temperatures will drop again tonight:
"So while it is a very cold morning this morning with plenty of clear spells and fine spells developing it will warm up for time this morning. temperatures getting above freezing in the next few hours still staying quite cold with highest temperatures of only a few degrees in the single digits. And again tonight will be cold again with temperatures dipping below freezing."
