Met Éireann has issued a snow and ice warning for the whole of Ireland with the possibility of heavy snow in places.
The status yellow warning comes into force at 3am on Thursday morning and will last until 11pm on Thursday night.
The national forecaster has warned that heavy snow in some parts of the country may cause “substantial disruptions”.
The State’s crisis management team for extreme weather held a virtual meeting on Wednesday to discuss the impacts of the expected snowfall.
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The meeting of the Department of Housing group included officials from local authorities, other departments, Met Éireann, and first response organisations.
In a statement following the meeting, the National Directorate for Fire and Emergency Management said officials would continue to “monitor the evolving weather situation”.
The group, who are due to meet again at 11am on Thursday, advised the public to prepare for possible heavy snow and icy conditions over the coming days.
The Road Safety Authority (RSA) has advised all road users to prepare for “hazardous” conditions on the roads and reduced visibility.
The RSA said motorists should check local traffic conditions and weather before any journeys during the poor weather.
Met Éireann forecaster Gerry Murphy told RTÉ News at One that parts of the country may be upgraded to an orange warning, but “it is difficult to pin down the exact places” where snowfall will be heaviest.
“Some areas will get enough snow to cause substantial disruptions,” he said.
The latest European Centre for Medium-Range Weather Forecasts (ECMRWF) model shows the snow shifting southwards on Thursday and Friday and falling with significant accumulations from Tralee across to Dublin with the highest accumulations in the Wicklow Mountains.
Rain, sleet and snow will spread northwards across the country on Wednesday night and Thursday morning driven by cold easterly winds leading to accumulations of snow in the northern half of the island.
This will bring with it hazardous driving conditions, travel disruption and poor visibility.
A status yellow low temperature warning will be in place from 9pm on Thursday night to 10am on Friday morning.
Met Éireann is also predicting that there could be significant accumulations of snow in Leinster, Cavan and Monaghan on Thursday night into Friday morning and have issued a snow-ice warning for those areas from 11pm on Thursday night to 7am on Friday morning.
A yellow snow warning will also come into place for the whole of Northern Ireland from 7am on Thursday morning to 2pm on Friday afternoon.
Parts of Cork and Kerry saw snowfall overnight with more snow expected in the coming days over many parts of the country.
Parts of the North had their coldest night of the year with a temperature of minus 8.6 recorded in Castlederg, Co Tyrone. The lowest temperature recorded in the Republic was minus 4 degrees at Finner Camp in Co Donegal.
The overnight forecast is for probable heavy snow in some places in the northern half of Ireland consisting of all the counties of Ulster and Connacht along with Longford, Louth, Meath and Westmeath.
Temperatures will be below freezing overnight in all places. An Atlantic front will meet the cold air after midnight, and rain, sleet and snow will spread from Munster into southern parts of Leinster and Connacht. The overnight temperatures will feel much colder with a significant wind chill factor.
“There is a little bit of snow overnight but the worst of the snow will be tomorrow,” said Met Éireann forecaster Joanna Donnelly. “There will be a north-south split. Snow will come up from the south steadily. There will be accumulations in north Connacht and Ulster.”
Ms Donnelly said the snow is likely to fall on the northside of a diagonal line running from Belfast to Galway. “The southern half of the country is more like to see rain and sleet.”
Met Éireann modelling shows accumulations of between 20mm and 30mm between Wednesday night and Thursday morning in the areas covered by the yellow weather warning.
Met Éireann is warning of “very hazardous driving conditions” on Thursday morning with poor visibility.
By tomorrow afternoon, sleet and snow will continue over Ulster, Connacht and north Leinster, but it will turn mainly to rain and sleet further south. Temperatures will range from 0 to 5 degrees but it will feel a lot colder than that because of the wind chill factor.
Friday will be the last day of the current cold snap. The night will be cold with severe frost and icy conditions developing, with possible sleet and snow over Munster and Leinster. Temperatures will range from minus 4 to 0 degrees.
The latest forecast shows a return to normal temperatures for the time of year between 7 and 12 degrees towards the end of the weekend.
