Gardaí in Waterford are urging motorists to drive with extra care this morning.
A nationwide status yellow fog warning is in place until 11am.
Officers in Dungarvan say the fog is particularly heavy there.
A single vehicle collision happened on the N25 at the Strandside roundabout in the town earlier.
Gardaí say no one was injured and they've cleared the crash.
They're asking motorists to be cautious and use fog lights when necessary.
Weather Alert
Level: Yellow
For Ireland
Dense fog in many areas overnight and for a time on Thursday morning.
Valid from 22:00 Wed, 22-Jan-2020
Valid until 11:00 Thu, 23-Jan-2020https://t.co/ozrQHtoOkt pic.twitter.com/tthRGy7ry5— Met Éireann (@MetEireann) January 22, 2020