Ireland remains in the grip of the worst cold snap in decades with road temperatures remaining below zero in many parts and further snowfalls forecast.
Motorists are being urged to exercise extreme caution in the icy conditions as councils struggled to grit secondary roads due to a shortage of salt.
Met Éireann predicted the cold spell would continue at least for the rest of the week with overnight temperatures plummeting to minus 8 degrees in some areas.
The cold weather is wreaking havoc with farmers with €15 million worth of potatoes and other produce destroyed, it was claimed tonight. Some 6,000 acres of potatoes across the country remain unharvested because of torrential rain in November and current freezing conditions.
The Irish Farmers’ Association said growers estimate that at least 75 per cent of crops will be lost to frost damage.
Up to five centimetres of snow is forecast for parts of Leinster, Connacht, and Ulster, already hit by ice after wintry showers and a severe overnight freeze.
Roads across the midlands and the northwest were said to be particularly bad with some councils running low on grit and salt.
Roscommon, Cavan, Leitrim, Meath and Westmeath county councils were said to have only enough salt to grit national routes, leaving many local and regional roads untreated.
Many gritted roads also froze again after overnight as temperatures dropped below minus 9 degrees in some counties.
The National Roads Authority said there were now satisfactory supplies of salt and grit to spread on the country’s main roads.
NRA spokesman Seán O’Neill said 4,000 tonnes of salt had been shipped to Limerick today and was being distributed to local authorities. The delivery yesterday of 4,000 tonnes of salt to Cork, along with 3,000 tonnes ordered from Carrickfergus, is also expected to ease the situation, he said.
However, Labour spokesman on transport Tommy Broughan condemned the Minister for Transport's response to the weather-affected roads.
"The shambolic and total failure of Transport Minister Noel Dempsey to co-ordinate gritting and other measures for the road network given the current extreme weather conditions has been an absolute disgrace," Mr Broughan said.
"Why as Minister did he not make sure that extra grit and salt supplies were coordinated at a national level to alleviate the treacherous road conditions that were forecast."
Knock airport was closed today between noon and 2pm due to what a spokesman said were blizzard conditions that saw 5cm of snow fall, more than twice the amount experienced at the airport over the Christmas period.
The airport is now open and operational, although the spokesman noted that flights to the airport from Liverpool and London-Gatwick were cancelled due to severe weather conditions in Britain.
Other flights from Luton, East Midlands, and London-Stansted have been diverted.
In a statement today, the Department of Education said it was a matter for schools' boards of management to decide whether weather and road conditions warrant the closure of schools, which are due to reopen this week.
"In making these decisions, schools should consider such issues as access and safety," the department said.
"Where days are lost during a school year due to bad weather or for other reasons - for example, heat or water systems failures - the board of management should make all reasonable efforts to make up these school days during the remainder of the same school year."
The statement added Bus Éireann would make locally based decisions relating to school bus transport services.
The AA said it had its busiest day yesterday, with over 700 calls for assistance by lunchtime. Car battery and electrical systems failures were four or five times greater than a typical Monday, the group said.
Hillwalkers are being urged not to venture up mountains without proper equipment. Speaking on RTÉ's Morning Ireland programme this morning, Gerry Christie of Kerry Mountain Rescue said "don't contemplate going up a steep mountain at the moment without an ice axe and crampons". He also warned hillwalkers to be mindful of alpine weather conditions on the mountains.
In Dublin, the Phoenix Park, the Chapelizod, Islandbridge and Knockmaroon Gates will remain closed until tomorrow due to icy conditions. Gardaí are also are urging motorists to avoid the Strawberry Beds and Tinkers Hill.
Due to continuing adverse weather and road conditions, a number of Bus Éireann services are affected.
In Northern Ireland, many schools and businesses were forced to close today, with many roads impassable due to ice. The Roads Service warned that not all routes would be ice-free, with many rural roads going unsalted.
Airports in Belfast and Derry were also hit by delays due to the wintry conditions.
Additional reporting: PA