Most parts of the country are expected to experience another cold night, with temperatures dropping to as low as minus eight degrees.
Met Éireann said it would be “very cold” tonight, with widespread severe frost and freezing fog in places.
Snow and ice, which made road conditions treacherous today, will not ease off until Christmas Day at the earliest, the forecaster said.
Temperatures of minus six degrees last night led to icy roads and extremely dangerous driving conditions throughout the country, AA Roadwatch said today.
All road temperatures are well below freezing again.
Some of the coldest spots are on the N6 Dublin to Galway road at Kilbeggan where the temperature is minus six, on the N3 at Butler’s Bridge, Cavan, where it is also minus six while in Wicklow. It is below minus five on the N11 at Arklow Bypass and on the N81 at Baltinglass.
Conditions are particularly icy on secondary roads and on higher ground throughout the country.
Motorists are advised that braking distances will be 10 times greater than normal due to the icy conditions.
In Wicklow, conditions are very icy on higher ground especially on the Killakee road and at Roundwood, while the Wicklow Gap and Sally Gap are both impassable.
Met Éireann haswarned patches of freezing fog will develop leading to hazardous driving conditions. Temperatures will fall to between minus one and minus seven degrees, with a widespread severe frost and icy stretches.
Met Éireann forecaster Deirdre Lowe said that it would be very cold across the country until the afternoon on Christmas Day when milder conditions are expected. “Everywhere will be freezing or below. The winds will be light. There will not be a coastal effect so temperatures will not rise,” she said.
Snow showers are expected today in Donegal and also along the southeast and east coasts, which have escaped the worst of the weather to date. Wintry showers there are likely to turn to sleet and snow later this evening.
The freezing conditions will persist for last-minute shoppers on Christmas Eve with temperatures not much higher than today.
Eamon Timmins of Age Action Ireland also warned older people to protect themselves during the cold snap and asked the general public to visit their elderly neighbours.
He said: “It is essential that older people aim at keeping the temperature in their homes at 18-20 degrees Celsius.
“Once the temperature falls below 16 degrees you are greater risk of respiratory illness, and if it falls below 12 degrees the blood thickens and your risk of heart attack and stroke increases.”
AA Roadwatch controller Nicola Hudson said that drivers travelling for Christmas should avoid secondary roads where possible as most have not been treated.
She said that motorists had taken heed of the warnings because there have been no major crashes since the cold spell started last Sunday. Only one road, a minor one in Co Clare, has had to be closed as a result of a collision caused by the bad weather.
“The majority of calls coming into the rescue centre are for flat batteries and non-starting vehicles. It looks like motorists are driving very carefully,” she said.
Motorists are also warned of minor crashes throughout the country as roads are treacherous. In Limerick a truck has jack-knifed on the Lees Cross/Rathkeale Rd (R518) between Lees Cross and Castletown Conyers is blocking the road.
Bus Éireann said the adverse weather conditions have caused disruption and delays to some of their services in the south west of the country. The company said services operating through the Killorglin area had been cancelled along with the following: Doolin to Galway, Doolin to Limerick, Doonbeg to Ennis and Galbally to Limerick.
Most Limerick city services are operating this morning with some delays.
Bus Éireann advised customers travelling in the southwest to contact their local travel office for information on individual services.
Cork, Dublin and Shannon airports have not reported any problems and the vast majority of flights departed Ireland on time. However, as the bad weather continues across Europe, some flights arriving into the country have been delayed - especially those from the smaller UK airports.
In the US the Federal Aviation Authority reported only general arrival and departure delays at some airports.