the Met Office has issued a yellow warning for snow and ice for most of Northern Ireland until noon today.
Only Fermanagh is unaffected by the Met Office alert, with hazardous ice and further snow flurries forecast as the spell of freezing weather continues across the British Isles.
Forecasters say there is a risk of injury from slips and falls on icy surfaces, and that some roads and railways are likely to be affected - with some cancellation of public transport services.
Ice and snow could make surfaces, including untreated roads, pavements and cycle paths, difficult in some areas.
Motorists have been advised to adjust their driving according to the conditions, by reducing speed and driving with extra care, even where roads have been gritted.
Even where roads have been treated, driving conditions may remain challenging, especially if there is a high risk of ice.
Conditions will be largely bright and cold today, according to the Met Office forecasters, but a widespread hard frost and freezing fog are expected for the early hours of Sunday. In England and Wales, travellers were hit by long delays and schools closed their doors as February began with the coldest night for seven years.
A coating of up to 14cm of snow caused havoc in the South West, forcing motorists to abandon their cars and seek shelter as traffic ground to a halt.
By late Friday evening, RAF Odiham in Hampshire had recorded 19cm of snow.
Flight disruption at airports in Cardiff and Bristol left queues of rugby fans facing a race to get to Paris ahead of last night's France vs Wales Six Nations opener.
The Met Office said a low of -15.4C (4.3F) was recorded just before midnight on Thursday at Braemar in the Scottish Highlands.
In the US, the extreme weather was blamed for around 21 deaths across the region, including people who appear to have frozen to death in Milwaukee, Detroit and Rochester.
Many more were injured by frostbite as a result of Arctic weather sweeping across the Midwest from the north.
Meteorologists say the record low temperatures have been caused by a 'polar vortex' - an area of freezing air breaking away from its normal rotation around the North Pole. Midwest temperatures have fallen to a bone-chilling -56C.
The intense cold forced airlines to cancel thousands of flights, with Chicago's O'Hare airport among the hardest hit.