Met Éireann has issued three weather warnings after temperatures dropped as low as -4C last night.
A status yellow freezing fog warning is currently in place and will remain until 12pm on Saturday.
The forecaster has warned people to expect "patches of freezing fog", which may cause hazardous driving conditions.
A status yellow ice warning has also been issued for the whole country and will come into effect from 7pm today, remaining until 12pm on Saturday.
Temperatures are again expected to dip as low as -4C in places, with predictions of "sharp frost and icy stretches" expected during the night.
Met Éireann has also issued a snow and ice warning for Co Donegal, which will remain in place until Saturday at 12pm.
This will bring a mix of scattered sleet and snow showers, with large quantities of snow expected on high ground.
Met Éireann has said that the bitterly cold and icy conditions are now likely to continue until the middle of next week.
The forecaster is warning "sharp to severe frost with icy surfaces" and "hazardous conditions" overall.
Snowfall was particularly evident in the north and east of the country on Thursday evening and early this morning.
The rest of today looks set to remain cold, with temperatures unlikely to exceed 4C.
Wintry showers will affect some northern and western coastal counties, with heavier downpours near the coast. Patches of freezing fog are also expected.
Remaining very chilly today with highest temperatures generally ranging from 0 to 5 degrees🌡️— Met Éireann (@MetEireann) December 9, 2022
Dry for many areas, although there will be some wintry showers, mainly affecting coastal counties🌨️🥶
Some patches of fog or freezing fog will also linger through this afternoon🌫️ pic.twitter.com/UNQB8po9AH
Met Éireann says that tonight will be similar to last night, with a widespread severe frost setting in from the late evening.
While many areas will be dry, some showers of hail and snow will affect Atlantic coastal counties. Temperatures tonight will fall to lows of between -5C to -1C in light westerly or variable breezes.
Saturday too will be generally dry with low winter sunshine, and isolated wintry showers.
Frost and ice will linger in unsheltered areas, with some patches of freezing possible.
The Road Safety Authority (RSA) is advising motorists and pedestrians to take extra precautions, particularly when driving on untreated road surfaces.
- Be on the lookout for pedestrians, cyclists and other vulnerable road users as snowfall may reduce visibility,
- Keep windows clear of snow during journeys,
- Manoeuvre gently and avoid harsh braking, acceleration or steering to minimise the risk of skidding,
- Use the highest gear possible to reduce the engine revs as this will help avoid wheel spin,
- And be aware brake times on icy surfaces can be up to ten times more than normal.
- Not underestimate the danger of frost and ice,
- Be aware that even if surfaces do not look particularly icy or slippery, black ice could be present and the surface may be slippery,
- Be aware that many slips and falls can occur in places people see as safe and secure, such as outside their homes or in their neighbourhood,
- Wear appropriate footwear,
- And wear high visibility clothing, carry a torch, and make sure any bikes used for cycling are fitted with suitable lights in the front and rear.
Dozens of flights out of Dublin Airport have been delayed this morning as a result of icy conditions on the ground.
The weather station at Dublin Airport saw lows of -2C last night.
The icy weather has seen many flights due to leave Dublin this morning delayed, with knock-on delays likely to continue for the rest of the day.
Several Ryanair flights have been affected, with passengers forced to wait on the runway for more than 3 hours in some cases.
Last night, Taoiseach Micheál Martin said the cold winter weather could put a tightness on the availability of the State’s energy supply but warned “we’re not over the worst yet".
However, he said the Commission for Regulation of Utilities (CRU) and Eirgrid have taken steps to work with high-energy users to manage pressures on the system.
Speaking on Virgin Media's, Mr Martin confirmed there is a programme in place in the event of tightness in energy supply in the coming days as Ireland braces itself for further sub-zero temperatures.
Meanwhile, bookmakers slashed their odds on the country seeing snow on Christmas Day this year.
Ladbrokes are now offering odds of 10/11 for there to be snow anywhere in the country on December 25, in from earlier odds of 4/6.
"It has been twelve long years since Ireland has experienced snowfall on December 25," said Nicola McGeady of Ladbrokes.
"If these latest odds are anything to go by, it seems punters could finally be getting their ‘White Christmas’ wish!"