WINTER is on its way back, forecasters have warned.
Temperatures are expected to plunge from the unseasonably mild highs of 13C in recent weeks to as low as minus 3C in the coming days.
The dramatic change in weather has prompted road safety chiefs to issue alerts to motorists about the dangers of frost, ice and fog for the rest of the week.
Met Eireann forecaster Pat Clarke said the shift signalled a return to normal conditions for this time of year, rather than any unusual switch in the climate.
"It's normal winter weather, but it's just a big change from what we had," he said.
Mr Clarke said daytime temperatures between 10C and 13C over the past few weeks - with night-time temperatures between 7C and 10C - were "very, very unusual" for late December and early January.
The mild conditions were a result of southerly winds bringing in rain and cloud.
"The last couple of weeks of mild weather might have fooled people to some extent," he said.
"But we are going to get a change now back to the cold."
While frost, ice and fog is expected, there is no imminent signs of any snow. Mr Clarke said it was too early to say if Ireland would escape widespread snow altogether this winter.
The cold snap is forecast to last until at least next week, with daytime temperatures between 7C and 10C.
After dark the mercury will plunge to between freezing and minus 3C.
"If the road looks polished or glossy it could be black ice, one of winter's worst hazards," said an RSA spokesman.
"Black ice is difficult to see. It is nearly transparent ice that often looks like a harmless puddle or is overlooked entirely.
"Watch out for black ice, especially in sheltered or shaded areas on roads, under trees and adjacent to high walls."
The RSA also called on anyone setting off on a journey in the coming days to check up-to-date weather forecasts, make sure their vehicle windows and mirrors are cleared, lights are working, tyres are checked and to slow down and drive gently.
Motorists were also warned to be on the look out for vulnerable road users such as pedestrians, cyclists and motorcyclists.