Hail and show expected later on Thursday.
Met Eireann has issued a Status Yellow weather warning for the entire country.
It will be bitterly cold today and again tonight with the likelihood of hail and snow.
It will be bright, cold and blustery today. Staying dry in the midlands, south and east for much of the day with sunny spells, but showers will occur across the north and west.
The showers will turn increasingly wintry with falls of hail and snow - especially in the north, and a few will push further south this evening. Northwest winds will be strong and gusty. Highest temperatures 4 to 7 degrees.
Tonight wintry showers will be widespread overnight and frequent in the north with accumulations of snow over inland parts of Ulster and other northern areas.
Mainly dry across the south and southwest. Northwest winds will stay strong and gusty.
A widespread sharp ground frost will form during clear spells with icy patches forming widely. Lowest temperatures -2 to +3 degrees, coldest inland in the north.
It will be very cold again on Friday. A few sunny spells, but with occasional wintry showers of hail, sleet and snow - further accumulations of snow over northern counties and over high ground elsewhere. Mainly dry in the south. Northwest winds will ease later. Highest temperatures of 3 to 6 degrees.