Major delays were reported on key commuter routes this morning because of icy conditions.
Emma Caulfield of AA Roadwatch said there was a spate of minor crashes this morning as a direct result of black ice, frost and freezing fog.
"Traffic was heavier on all key routes from first thing, in particular on the N3 into Dunshaughlin and the Clonee bypass and travelling to Dublin via Ashbourne on the N2, and delays continued until well after rush hour", she said.
A number single-vehicle crashes, as well as a serious incident that closed the Strokestown Road, were reported in Co Longford.
The AA reported a large number of call-outs from motorists whose cars needed towing after skidding off the road.
Motorists were warned that similar conditions could be expected for the next number of nights.
"With very low temperatures and dense fog forecast for Monday night, it is possible that road conditions will be very dangerous," Ms Caufield added. "Motorists should take particular care when driving overnight and in the early hours of the morning."