Met Eireann have warned a sub-zero "polar air mass" is set to hit Ireland as temperatures plummet.
Freezing cold conditions are expected as values fall across the country over the next few days.
The national forecaster wrote on Twitter on Saturday: "A cold polar maritime air-mass is moving in over Ireland today.
"Sunday morning (0600UTC) 850hPa temperatures (around 1.5km above the surface) will be sub-zero nationwide & nearing -5°C in the NW of the country.
"Frost is expected to form in some sheltered areas by Sunday morning."
And it looks like a freezing week is in store as the mercury will drop as low as 0C for three of the next four nights.
During the day however temperatures will stay steady around 7C-10C for the next week.
A Met Eireann forecaster said: "This morning, rain in Connacht and Ulster will extend south-eastwards and will gradually clear to the southeast around noon. Sunny spells and scattered showers will follow.
"Highest temperatures of 8 to 11 degrees with moderate to fresh southwest winds, becoming westerly as rain clears.
"Tonight, scattered showers will mostly die out in Leinster and Munster, but will continue in Connacht and Ulster. Clear spells in many areas and some patches of mist, but becoming cloudier in the south, with perhaps some coastal drizzle. Lowest temperatures of 0 to 4 degrees with frost developing in places.
"Sunday will be cool and bright in most areas with sunny spells and scattered showers, mainly over the western half of the country.
"It will be mostly cloudy in southern coastal counties with a little patchy rain or drizzle in coastal areas. Highest temperatures of 6 to 9 degrees with moderate west to southwest breezes.
"Sunday night will be mainly dry, though there may be one or two coastal showers. It will be cold with lowest temperatures of 0 to 4 degrees and a touch of frost in places, mainly over the eastern half of the country."
Next week is set to be much the same with plenty of rain during the day and freezing weather overnight.
The forecaster added: "Monday will start off dry with some sunny spells. It will become cloudier in the west with rain moving in over Connacht and Ulster in the afternoon and evening. Highest temperatures of 9 to 11 degrees with moderate to fresh southerly winds. On Monday night, rain will affect much of Ulster, Connacht and west Munster. Lowest temperatures of 5 to 9 degrees.
"Tuesday will be mostly cloudy with persistent or heavy rain over the western half of the country and with showers further east. The rain in the west will extend eastwards through the afternoon and evening with clear spells and a few showers following on Tuesday night.
"Highest temperatures of 10 to 12 degrees with fresh southerly winds, becoming westerly and easing as rain clears. The night will be cold with lowest temperatures of 0 to 4 degrees.
"Wednesday will be mainly dry with sunny spells and perhaps a few light showers near west and north coasts. Highest temperatures of 7 to 9 degrees with light westerly breezes. Wednesday night will be cold and dry with lowest temperatures of -2 to +2 degrees and with frost in many areas."
