Met Eireann has issued an 18-hour weather warning ahead of a sudden change in conditions.
A freezing Arctic blast is set to hit within hours and will linger well into next week.
Temperatures could drop as low as -6C at times, with wintry showers of hail, sleet and snow also forecast.
READ MORE: Ireland snow storm track as Met Eireann forecast rare weather event before big change
This could lead to severe frosts and icy stretches on roads, with the public urged to prepare for “hazardous” travelling conditions.
The national forecaster also warned that there could be some patches of “freezing fog”.
Freezing fog is considered a rare weather event because specific circumstances are required for the fog to form. The fog consists of ‘supercooled’ water droplets, which means the moisture remains liquid despite temperatures being below freezing.
A Status Yellow weather warning for Ice has been issued for the entire country. It comes into effect at 6pm Sunday and lasts until noon Monday.
The alert reads: “Icy stretches are likely on Sunday night and Monday morning. Hazardous travelling conditions are expected, especially on untreated roads and footpaths. Some patches of freezing fog are also possible.”
The imminent cold weather has also prompted Met Eireann to issue a nationwide ‘Winter Weather’ advisory, which lasts until noon on Thursday.
It reads: “Turning cold across the country between Sunday evening and Thursday morning as an Arctic airflow becomes established, bringing sharp to severe frosts and icy stretches on roads and footpaths. Some showers of hail, sleet and snow are expected with the potential for freezing fog.”
Ireland day-by-day forecast
Sunday
Met Eireann said: "Mostly cloudy today with some showery outbreaks of rain or sleet. Also a slight chance of thunder and hail, mainly in the northwest. Highest afternoon temperatures of 4C to 7C . Moderate westerly winds, gradually easing light.
"Cold tonight with a widespread sharp frost and icy stretches. Temperatures will fall to between -3C and 1C towards morning, lowest in Ulster. Scattered wintry showers will continue for a time, most frequent in Atlantic coastal counties, generally clearing later in the night. Some patches of freezing fog also possible in light northwesterly or variable winds."
Monday
The national forecaster continued: "Staying dry in most areas tomorrow with patches of frost and ice lingering through the morning. There will be a few showers of sleet, generally along Atlantic coastal areas, with isolated snow flurries also possible. There will also be occasional sunny spells, mainly towards the east. Highest temperatures of 1C to 5C in light and variable breezes.
"Widespread sharp frost with temperatures falling to between 0C and -4C or -5C . Clear spells with scattered wintry showers. Outbreaks of sleet and snow may affect parts of the west and south too. Some freezing fog will likely form with little wind over land."
Tuesday
The forecast reads: "Cold with lying frost or ice. There will be some sleet and snow showers in places. Bright or sunny spells too. Afternoon temperatures of just 1C to 4C with light to moderate variable or northerly breezes, fresher near Atlantic coasts. Lowest temperatures of -2C to -6C overnight with further sleet and snow showers. A sharp to severe frost with icy stretches and lying snow in parts. Some freezing fog patches too."
Wednesday
The meteorological service said: "Sunny spells with scattered wintry showers, mainly in the west and north. Highs of 3C to 6C but feeling very cold in a brisk northerly wind. Temperatures will likely fall below zero again on Wednesday night."
Further outlook
The forecast concludes: "Turning much milder on Thursday with a spell of rain and fresh southerly winds moving in from the Atlantic. The rain will be preceded by some sleet and hill snow for a time in the north and east.
"Friday looks fairly dry and bright with temperatures of 5C to 10C , coldest in the northeast. Mild and changeable for next weekend with temperatures around 8C to 10C."
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