Drivers are being advised to slow down and stay off the roads tonight if they can because of thick fog.
Met Éireann earlier issued a status yellow warning for all counties in Munster and Leinster and Connacht.
The forecaster is warning of significant "Fog thickening this evening with some dense areas of fog this evening and tonight."
Very foggy conditions have already been reported in Limerick, Tipperary, Kildare, Meath, Wicklow and Offaly.
The AA has asked any drivers making essential journeys in affected areas to take extra caution and to reduce speed, and use fog lights where necessary.
The warning is now in effect and will remain in place until 6am tomorrow.
Fog Warning has been issued— Met Éireann (@MetEireann) November 29, 2020
Location: Munster, Connacht & Leinster
Valid: until 6am Monday morning
For full details please see https://t.co/ZsjQsKCXDy or our Android and IOS apps pic.twitter.com/TUkLRRuvqa