A status orange snow and ice weather warning has been issued for five counties.
A snow and ice warning has been issued for Clare, Cork, Limerick, Tipperary and Waterford from midnight until 12pm on Thursday.
Met Éireann has warned of very difficult travelling conditions, poor visibility, travel disruption and animal welfare issues.
A nationwide yellow warning for low temperatures and ice remains in place until 10am on Wednesday with the same warning in place from 8pm until 10am on Thursday.
Wednesday will be dry with sunshine for many but scattered showers of sleet and snow will continue in the north and northwest.
It will be cloudier in the afternoon with a spell of heavy rain moving into the west and southwest, turning to hail, sleet and snow at times as it spreads inland.
Afternoon highs of just three to six degrees in light northwesterly or variable winds.
It will turn very cold overnight, with scattered wintry showers continuing in Ulster and north Connacht.
Lowest temperatures of -4 to 0 degrees in light to moderate easterly or variable winds, with widespread frost and ice developing.
Thursday will see outbreaks of rain, sleet and snow will clear to the south in the morning, leaving another very cold day with showers of rain, sleet and snow, most frequent across Connacht, Ulster and west Munster.
Temperatures will reach just one to four degrees.
