Heavy snow and ice has caused disruption in many parts of the UK after arctic conditions returned.
Northern Ireland had its coldest day on record on Saturday with temperatures at Castle Derg climbing no higher than -11C, beating the previous record of -9C.
Temperatures will struggle to get above freezing on Saturday night, with at least -15C (14F) expected overnight in parts of Scotland and Northern Ireland.
Forecasters say the cold conditions will remain into next week.
November saw the UK's most widespread snowfall since 1965, and December has continued to be exceptionally cold and snowy.