Disruption from snowfalls to motorists, airline passengers and other commuters is expected to increase today as the New Year travel period begins.
The heavy snow showers are expected to ease this evening, but with temperatures close to freezing the thawing process will be slow.
Amid renewed safety warnings yesterday, it was confirmed the cold snap had claimed its first victim, a 92year-old woman who died in north Donegal, one of the worst affected areas.
She was found frozen to death outside her isolated home in Annagary.
Bus Eireann services were among those worst hit yesterday, with no buses running between Dublin and Cork, Galway and Belfast for most of the day. Some local services were also cancelled, and city bus services in Cork, Limerick and Galway were severely curtailed.
Galway, Sligo and Donegal Airports were also closed yesterday, but Knock, Shannon and Dublin remained open.
The Army collected nurses from outlying areas for the 600bed Cork University Hospital which was down to 20 nursing staff because of those stranded by the conditions.
A spokesman for Bus Eireann said it could not guarantee operations until the weather improved. "We'd advise people to check with their local office," he said.
Gardai reported a spate of minor accidents around the State, particularly in the midlands, west and north. The Dundalk-Newry road became blocked off last night when vehicles jack-knifed on either side of the carriageway.
Gardai reissued warnings not to travel unless necessary and for people to keep a close eye on elderly neighbours.
The heaviest snowfalls yesterday were in the north-west and midlands, with 19 cm falling in Knock by 6 p.m., compared to just 1 cm at Dublin Airport.
Northern Ireland meteorologists said it was the heaviest snowfall since 1983. More than 15 cm of snow fell in Belfast in 2 -1/2 hours on Wednesday night, the coldest on record this year.
Air temperatures reached minus 13 degrees in south Belfast and minus 8.6 degrees in Clones, Co Monaghan. Across the North drivers abandoned their cars and walked home as roads became impassable.
Met Eireann said the next few days would be very cold and mostly dry with frost in places. At the weekend there would be rain, preceded by snow, and strong winds, possibly with gales at sea.
Aer Rianta, meanwhile, defended its handling of the closure of Cork Airport yesterday, after some passengers claimed it did not make enough effort to clear the runway.
A spokeswoman said staff had worked "around the clock" using snow-ploughs to reopen the airport, which they succeeded in doing in the afternoon. Cork was on much higher ground than other airports, making it more difficult to clear, she said.
She added that the company was adopting a wait-and-see approach to services today. Passengers on UK flights have been advised to contact their airlines.
Delays of up to three hours were caused early yesterday by the temporary closure of Britain's Gatwick and Stansted Airports.
