Temperatures will fall to -3°C or -4°C on Saturday night, with Met Éireann issuing a status yellow low temperature/ice warning for Connacht, Leinster, Munster, Cavan and Monaghan.
There are no warnings in place for Donegal or Northern Ireland.
The warning is in place from 9pm on Saturday night until 11am on Sunday morning.
It will be coldest around dawn on Sunday and temperatures will remain below freezing until mid-morning.
Overall, Sunday will be a dry and bright day, with good sunny spells in most areas. Highest temperatures will range from 4°C in Ulster to 8°C in Munster in mostly light southerly breezes, Met Éireann said, but becoming fresher near west and northwest coasts.
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