Status Orange and Status Yellow warnings are in place in Ireland.
A status orange warning for snow and ice issued for counties Clare, Limerick and Tipperary has also been extended to Galway.
Met Éireann warned of "heavy" snow overnight in the counties under the warning, which came into effect from midnight to midday.
A special status orange warning for snow and rain was in effect for counties Cork and Waterford from midnight, warning that "heavy rain will change to sleet and snow".
A status yellow low temperature and snow warning is in place across the country until tomorrow afternoon, with temperatures expected to drop to -4C tonight.
A special status yellow snow and ice warning was in place for 14 counties from 9pm to midday last night, with Dublin, Mayo, Roscommon, Longford and Westmeath also in place.
Rain, sleet and snow will continue to spread from the W tonight,
— Met Éireann (@MetEireann) November 20, 2024
with a chance of accumulation 🥶 https://t.co/BgwnlFfuRb https://t.co/lvQFgW9biq pic.twitter.com/q7ylgTp7OQ
In Northern Ireland, a yellow ice warning is in place for counties Antrim, Armagh, Down, Fermanagh, Tyrone and Derry until 10.00am.
The Met Office has said that winter rains and icy surfaces will cause travel problems. Met Éireann said snow was expected to cause hazardous travel conditions, poor visibility and travel disruption.