Dublin Airport may have to close again over the coming days as the country remains gripped by an "exceptional" cold snap which is expected to last until Thursday at least.

Up to 30 flights in and out of Dublin airport were suspended from 6am yesterday morning as heavy snow falls overnight froze quickly and made the runways unsafe. Flights resumed at 8am but there was a knock-on effect for the rest of the day.

"If similar conditions apply over the next few days as has been forecast then it remains a possibility that the runways will be closed again. This is not a decision we take lightly but is done for safety reasons," said Siobhan Moore of the Dublin Airport Authority. Although extra staff had been called in to help clear the runways, nothing could be guaranteed, she said.

Evelyn Cusack of Met Eireann said that the "exceptional weather" for this time of the year was caused by an "Arctic plunge" which had spread all the way down Europe to the Alps.

"It will continue until Thursday at least with night-time air temperatures plunging to -8ºC and ground temperatures to -10ºC. Snowfalls were possible along the west and east coasts, she said.

Sean O'Neill of the National Roads Authority assured motorists that the country had "ample salt" supplies to cover all the main national roads and would be gritting all main roads twice a day while the Arctic conditions last – in the evening and first thing in the morning.

"The NRA bought in tonnes of salt in July and we got good value. We're ready," said O'Neill.

Answering criticisms that several of the country's national roads were not in fact gritted by Saturday morning, O'Neill said that as far as the NRA was concerned all local authorities had gritted the main roads on Friday night.

"But you will always get slippage even if a road is salted," said O'Neill.

There are a total of 92,000km of roads in Ireland of which around 16,000km are national roads, with the remainder regional roads. Priority will be given to the national roads – those roads with 'M' or 'N' in their title – and gritting of the regional and link roads will only take place once the main roads are safe.

There are also 300 snow ploughs on standby in case heavy snowfalls need to be cleared off the road.

Transport minister Noel Dempsey pleaded with motorists not to take any unnecessary journeys and to use public transport where possible.

Representatives from the public transport companies – Dublin Bus, Bus Éireann, Irish Rail and Luas – all expressed confidence yesterday that a full service would be maintained through the cold snap as long as the situation didn't deteriorate any further.

They all, however, pleaded with the public to check the relevant websites before setting out on any journey.

Dublin Bus said that while it had to make some diversions on account of slippery roads around the Dublin mountains, it had its own supply of grit and was confident of maintaining a full service.

Bus Éireann was forced to cancel some routes in the Navan area on Saturday morning but was also confident a full service would be maintained. Irish Rail expressed similar confidence. A Luas spokesman said it would take a snowfall of 30cm to stop the service.

Dempsey encouraged people to look in on elderly neighbours. Following concerns last year that clearing pathways outside private houses may have made householders liable for people who fell, the minister revealed that the government had received advice that no liability was involved as long as clearing a pathway didn't create a greater hazard elsewhere.

"It's a matter of common sense," said Dempsey The minister, who called a meeting of the transport section of the government's emergency planning committee early yesterday morning, admitted that the quick response this time was a result of lessons learned last year.

Last January, when a similar cold snap brought the country to a standstill, the government had to await the return of Dempsey from his holidays in Malta.

"You'd be a bit stupid if you didn't learn from that," said the minister, who added that he had no holiday plans.