Wednesday night will bring freezing rain - which will lead to extremely dangerous road conditions.
That is the warning from Met Éireann, which has two Status Yellow alerts for wintry conditions on its website.
The first begins in the early hours of Thursday and the second takes effect that night into Friday.
Meteorologist Joanna Donnelly explained what freezing rain is and why it's different to snow.
She told Newstalk: "Freezing rain falls through a layer of the atmosphere, it's a warm front coming through and it's a pocket of warm air.
"The snow or the ice crystals in the air, transfer back, they melt back into the liquid... the liquid then falls back into the freezing air right near the surface, and before it has a chance to turn into an ice crystal, it lands on the ground.
"I'm very pleased with myself for explaining that correctly, it falls into the ground and spreads into the slippiest thing on the surface of the planet."
On Sunday, Met Éireann issued a winter weather advisory, warning that an Arctic airmass will set in later this week, bringing a sharp fall in temperatures.
"Showers of hail, sleet and snow will occur during the second half of the week," the forecaster said, adding: "Updates with potential warnings will be issued in the coming days."
Carlow Weather's Alan O'Reilly has also been keeping followers up-to-date on how the cold spell will pan out.
Tweeting this morning, Alan said: "Temperatures down to -3.5c with some showers in Northern areas. Temperatures near coasts are higher and some areas have escaped the frost this morning. Temperatures staying low today and widespread hard frost tonight."
Temperatures down to -3.5c with some showers in Northern areas. Temperatures near coasts are higher and some areas have escaped the frost this morning. Temperatures staying low today and widespread hard frost tonight. pic.twitter.com/grCaCL1kBO
— Carlow Weather (@CarlowWeather) December 7, 2022