Road chiefs have refused to give a green light to people driving home for Christmas as the big freeze is poised to strike again.
Temperatures are expected to plunge as low as minus 10C in the coming days with more snow threatening further transport chaos across the country.
Sean O'Neill, of the National Roads Authority (NRA), urged people not to panic but cautioned road grit is being rationed and public transport may be the only option for people travelling home for the holidays.
"We'll keep the national routes open and running, but if you have to go off to a local road for an extensive period of time then you really need to talk to local authorities to see how that road is," he said.
Met Eireann has issued a severe weather warning that cold and wintry conditions will sweep across the country in the days ahead and right through next week.
Forecaster Joan Blackburn said snow will return first to Ulster, Connacht and west Munster - with the north and west to be worst hit in the run up to the weekend - before shifting to the east and south from Sunday.
The mercury will drop to between minus 5C and minus 10C at night with widespread frost, ice and freezing fog making conditions hazardous for motorists.
Mr O'Neill, of the NRA, said drivers needing to use minor roads next week were at the mercy of the weather as plunging salt levels means grit is being strictly managed.
"We are in a historical, unprecedented weather demand and obviously that means salt gets used up," he said.
The early cold snap has already eaten up 75,000 tonnes of supplies at an estimated cost of around 10 million euro, with just 15,000 tonnes left. Normally, road authorities use 60,000 tonnes during an entire year.