Senior Forecaster for Met Éireann Gerry Murphy said it looks like the cold weather will last through next week.
"We're really at the start of potentially a long cold spell because really this cold weather is set to last all the way through next week," he said.
Speaking on RTÉ's Six One News, he said this means freezing fog, severe ice and frost as well as very cold days and wintry showers at times will persist.
He said where it does snow, it will accumulate over time.
Most counties remain under weather warnings tonight, with a mixture of scattered sleet and showers as well as icy stretches and freezing fog adding to a day of travel disruption.
Met Éireann expects sharp frost and icy stretches to set in tonight as temperatures dip to -4C in places.
A Status Yellow freezing fog warning applies for all counties in the Republic of Ireland until midday tomorrow, causing potentially hazardous driving conditions.
That is coupled with a Status Yellow warning for ice in the same counties also in place until midday tomorrow.
An additional Status Yellow warning for snow and ice applies specifically to Donegal, with Met Éireann warning that between 9pm tonight and midday tomorrow that "scattered sleet and snow showers will give some accumulations, especially on high ground".
The UK Met Office is responsible for weather warnings in Northern Ireland and has placed Antrim, Down, Tyrone and Derry under a Status Yellow warning for Ice until midday on Sunday.
The warnings are on top of a general winter weather advisory currently in place until Wednesday next week.
That advisory states it will "remain very cold into the middle of next week due to an Arctic airmass, bringing sharp to severe frosts, and ice or black ice on roads and footpaths".
"Some showers of hail, sleet, and snow will occur, mainly in coastal counties. Freezing fog is likely at times, especially this weekend. Winds over land will remain generally light," it added.
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The freezing weather has seen a total of 143 flights cancelled at Dublin Airport.
A spokesperson from daa, which operates Dublin Airport, said 74 inbound flights and 69 outbound flights have now been cancelled.
Five incoming flights were also cancelled.
A number of flights were delayed as a result of the weather.
A spokesperson for the daa said that the issue is to do with de-icing of planes which is looked after by the airlines themselves.
He said that there will be a knock-on impact felt throughout the day as a result of this.
Passengers are advised to check with their airlines directly for up-to-date information on their specific flights.
Aer Lingus has advised its customers to arrive at Dublin Airport and check in as normal.
It said that any customers whose flight has been cancelled will be contacted by the airline's customer care team.
The weather conditions caused further disruption to public transportation services, with both Dublin Bus and Irish Rail saying that a number of services this morning have been either delayed or cancelled. Delays remain on the Luas red line service.
Bus Éireann said it had to cancel a number of scheduled services and a small number of school transport services in the western region.
The lowest temperature reported at a weather station this morning was at Mount Dillon in Co Roscommon, where -7C was recorded at 8am.
-5C expected overnight
Met Éireann said a widespread sharp to severe frost has already developed in many areas this evening and some icy stretches are possible on untreated roads as freezing fog becomes more widespread in light westerly or variable breezes.
A scattering of wintry showers are expected mostly near northern and western coasts but one or two may meander further inland at times also.
Lowest overnight temperatures of -5C to -1C, according to Met Éireann.
The forecaster said tomorrow will be generally dry with low winter sunshine, and isolated wintry showers.
Frost, freezing fog and ice will linger in some areas.
However, highest temperatures of only 0C to 4C are expected in light variables breezes.
'Let people know your route'
AA Ireland Head of Communications Paddy Comyn advised motorists to slow down to avoid accidents.
He said people should leave a gap to the car in front and make sure their movements are "slow and deliberate".
Speaking on RTÉ's Morning Ireland, Mr Comyn said people can pack some essentials in their car to make the journey safer.
He advised people that they should keep a blanket in their cars, saying that it is "great obviously if you do have a breakdown provider" as well as keeping the mobile phone charged, keeping a shovel in the car if in hilly areas and to "let people know your route as well".