Gardaí have again urged drivers to exercise extreme caution as icy roads and freezing fog continue to make driving conditions treacherous.
Freezing overnight temperatures again left ice and snow on many roads across the country.
Gardaí today urged drivers in several counties not to make unnecessary journeys and to watch out for snow, black ice and freezing fog.
Gardaí confirmed there had been several collisions, including a fatal crash near Gorey in Wexford.
An ambulance attending the crash overturned on the way to the scene and several other vehicles collided as a result of the initial crash.
The N11 road from Bray to Wexford was described as "extremely dangerous and icy".
AA Roadwatch reported that icy conditions were continuing to cause problems for motorists in several parts.
Freezing fog around Roscommon town and Tullamore in Co Offaly were particularly bad, the organisation said.
Temperatures as low as -10 degrees are expected this week with no part of the country escaping the expected freezing weather.
Ice caused the closure of the Bandon/Timoleague Road in Cork for a while yesterday after a collision and there are dangers from ice on secondary roads around Fermoy, Macroom and Mallow.
Parts of Leitrim and Roscommon are badly affected and best avoided. The Lurgenboy to Manorhamilton Road was closed and motorists have been advised to avoid routes in the Castlerea and Ballaghaderreen areas.
An AA Roadwatch spokeswoman said some roads were frozen so long from the previous cold snap that they did not thaw when temperatures rose on Christmas Day and St Stephen's Day. She urged motorists to continue avoiding secondary roads where possible.
The conditions are causing difficulties for pedestrians as well as motorists.
Cork University Hospital (CUH) has reported a rise in fractures and breaks as a result of falling on snow or ice.
Other casualty departments have been inundated with injuries as a result of the conditions.
A senior consultant in emergency medicine is urging pedestrians to exercise caution in the current icy conditions.
Prof Stephen Cusack, who heads up CUH's emergency department, says that since the cold snap began they have been inundated with people suffering dislocations, minor fractures and sprains after falls. Prof Cusack says people should be aware of the need to tread carefully, especially on pavements, driveways and garden paths.
"We have had the equivalent of a slow burning major incident. We have had over 55 people admitted with orthopaedic injuries [at CUH] following slips on the ice. This is roughly the equivalent of two weeks of regular trauma work in this hospital.
"It is quite extraordinary and people really need to be very careful.
The weather patterns which brought snow to the north of the country in the build-up to Christmas is likely to be reversed in the coming day with snow and ice most likely to be concentrated in the south. Temperatures fell to seven degrees below zero last night and will rise no higher than five degrees today.
A band of rain is likely to fall as sleet or snow in the south and southeast as temperatures plummet to well below zero tonight.
Easterly winds will be replaced by winds from the Arctic, adding to the chilling effect as New Year approaches.
Parts of the west and north are likely also to experience falls of snow closer to the weekend.
A white Christmas was reported in all of Ulster and as far south as Longford with lingering snow and ice.
However, there was little by way of fresh snowfall, which is the technical definition of a white Christmas as far as meteorologists and bookies are concerned.
Rising temperatures, as forecast, put paid to most people's hopes of the first white Christmas since 2004, but the mild spell, which southern and eastern parts of the country experienced in recent days, has been replaced by much colder weather.
"Anybody that is in anyway unsteady on their feet should just not be outside in this weather. Please, please do not go out walking."