Met Eireann has said it may snow in parts of Ulster today.
In its latest weather forecast, the meteorological service said it will be cold on Friday with sunny spells and scattered showers generally.
These showers will mainly be of rain or hail, but up north sleet or snow may occur in parts of Ulster, though Met Eireann notes "any accumulations will be limited".
Highest temperatures of only 4 to 7 degrees, in light to moderate westerly breezes, fresher along northern coasts.
The mercury will plummet tonight, as it's set to be cold, calm and clear with a widespread sharp to severe frost in icy stretches.
The forecasters said lowest temperatures will widely fall back to -3 or -4 degrees.
There will also be some fog later too, mainly in the southwest midlands.
On Saturday then, the frost and fog will clear for a dry, calm and mostly sunny day.
But it will be cold throughout the day, with temperatures only getting from 3 to 7 degrees in the afternoon.
Saturday will again be freezing and frosty, with temperatures widely falling to -3 or -4 degrees.
Met Eireann's outlook for Sunday and early next week is as follows:
"Generally dry and calm with high pressure in charge.
"However, it will be duller early in the week with patchy light rain.
"Less cold too though, with frost and ice limited to where skies break by night.
"Mist and fog at times with slack winds.
"SUNDAY: A sharp to severe frost to start the day, but overall dry and sunny with just light breezes. Highs of 4 to 9 degrees, coldest across Ulster and north Leinster.
"MONDAY: Frost clearing on Monday to give a mostly dry day with a mix of cloud and sunny spells, brightest across the midlands and southeast. Less cold, with highs of 7 to 10 degrees, in light to moderate southwest breezes.
"TUESDAY: Some frost further south to begin the day. A duller day everywhere with patchy outbreaks of rain, mist and local fog too. Highest temperatures 9 to 11 degrees in light variable mainly westerly breezes."
