Met Eireann has issued another severe weather warning with up to 20 centimetres of snow forecast over the coming days.
Forecasters said this coming cold snap will be worse than the one two weeks ago, with severe disruption likely.
Snow showers will develop this afternoon over Ulster and Connacht and will continue falling tonight and tomorrow morning.
More significant snow falls are expected tomorrow afternoon, on Friday night and for a time on Saturday - with a band of heavy snow spreading across the country from the west and northwest.
It is likely that no area will escape.
Joan Blackburn of Met Eireann says conditions will worsen over the next 24-36 hours.
She said all areas of the country could expect a band of snow for a time, beginning from midday tomorrow and extending into Saturday.
"Pretty significant snowfall is expected, with falls of between 10 and 20cm in places."
Transport Minister Noel Dempsey said the focus for the Government is keeping the primary routes open.
His comments come despite criticism of the condition of secondary roads and housing estates following the last cold snap.
But Minister Dempsey said the main roads cater for 80% of commercial traffic, and that has to be the priority.
"Salt stocks have to be prudently looked after," Minister Dempsey said.
"We have supplies coming in - a little bit later than expected, but that's why we have to be prudent."
Bookmakers Boylesports are already paying out on a white Christmas in Dublin, Cork and Belfast - a move that will cost them a five-figure sum.