The weather will turn milder as we head into the weekend, but not before more freezing conditions on Friday.
A status orange low temperature/ice warning is in place for 16 counties, while a status yellow low temperature/ice warning remains in effect for the rest of the country.
It will be extremely cold on Thursday night with temperatures below -5° expected away from coastal areas, leading to severe frost and ice.
Patches of freezing fog will also lead to hazardous driving conditions in places.
People are also being asked to be aware of treacherous conditions on paths and roads, as well as increased risks to vulnerable people and animals.
Alan O'Reilly from Carlow Weather told The Hard Shoulder there is some relief in sight.
"A good bit of relief [is] coming, but temperatures-wise and also the wind will blow those turbines to generate some renewable electricity," he said.
"It's going to turn much milder but wetter, I'm afraid, but also windy over the weekend.
"Unfortunately we've a bit to go before that."
'Still very cold'
He said Thursday night will continue to see very cold temperatures.
"We've a very cold night tonight, temperatures still going down below -5° in many areas," he said.
"Not as cold in the north-west or the west coast, or even on the east coast, but still very cold.
"We have the freezing fog returning, unfortunately, there's going to be some fog tonight and into the morning.
"That's going to make for a tricky start on Friday for many people."
Alan said conditions could be worse on Friday night.
"It's still going to be bitterly cold tomorrow, but we're also going to have some showers.
"They're going to be rain and sleet a lot of the time coming in from the north-west... and they will fall as snow in some higher ground tomorrow evening.
"The areas in the shade today didn't thaw at all - so you've cold night tonight [and] another cool day tomorrow.
"Even if it's sleet or rain that falls, you're likely to have icy conditions in some places - so it's going to be tricky tomorrow night," he added.