Forecasters today predicted the coldest December on record with more snow on the cards and biting temperatures lasting at least six days.
The north and west have borne the brunt of the latest wintry conditions but snow is to spread across the country overnight with up to 10cm expected in northern parts.
Road chiefs claimed salt supplies were being used to keep national roads open but admitted concerns among local authorities about regional and back routes.
Dublin City Council said water restrictions would remain in place but vowed to have a full supply over Christmas week.
Met Eireann forecaster Gerald Fleming said the latest cold snap could make December 2010 a record breaker.
"It's certainly looking that this December, in terms of our records in Met Eireann, could well turn out to be the coldest December on record, it's heading in that direction," he said.
Temperatures plummeted as low as minus 4C last night with snow hitting counties across Northern Ireland as well as Donegal, Mayo and Galway before spreading inland to Longford, Cavan, Roscommon and Offaly.
Mr Fleming said showers will affect all areas tonight and particularly the east coast tomorrow as the weather front moves out to the Irish Sea.
He could not say which areas will be the worst hit, but predicted the early days of next week would likely be dry but cold.
He said temperatures may begin to gradually rise on Wednesday or Thursday, but admitted the second big freeze of the winter could continue into Christmas week.
The National Roads Authority said there are 14,000 tonnes of salt to grit national roads until another shipment of 25,000 tonnes arrives at the middle or end of next week.
"We have to prudently manage what we have so we can get us there," spokesman Sean O`Neill said.
Mr O'Neill said they had enough supplies to last them for seven days.
He warned attention would be given to national roads until fresh supplies arrive, admitting local authorities were coming under pressure to keep back roads clear.
Dublin City Council said that despite recent water restrictions supplies still needed to be conserved.
Michael Philips, city engineer, said: "While restrictions in water have been going on, we have not achieved the savings we had hoped to save.
"This gives you an indication of the number of broken water mains there are in the ground."
He said there were seven broken mains but pledged households and businesses would not have their water cut between December 23 and 28 as long as supplies were conserved until then.
Bus Eireann said the vast majority of its services are operating, with delays in parts, while Iarnrod Eireann said its trains are all running but warned of delays as snow spreads across the country.
Drivers were urged not to make trips over the coming days unless necessary, and households and businesses were asked to clear snow from pavements before it freezes.