Temperatures dropped to -5C on Monday night as snow and sleet fell on already treacherous surfaces, with the north west of the province particularly badly hit.
An unprecedented number of patients requiring surgery after falling on ice has led to one health trust having to cancel several planned operations.
Altnagelvin Hospital in Londonderry has treated 102 people who required surgery after slipping on ice in the past fortnight.
The Western Health and Social Care Trust has postponed 26 planned operations as a result.
Staff at accident and emergency departments in Belfast's Royal Victoria Hospital and at the Ulster Hospital in Dundonald are also experiencing an increase in patient numbers. Over the past week at the Royal 75 people who had sustained fractures will require further treatment. Meanwhile Roads Service has issued an urgent warning to motorists amid predictions that the icy spell would last for at least another week.
“We are getting ready for another very cold night across Northern Ireland, we are expecting snow showers and further accumulation in the morning. This is one of the coldest periods in 30 years and it looks like we will be suffering those conditions for around 10 days,” said Colin Brown from the Roads Service.
There has also been confusion over who is responsible for gritting pavements, while reports are flooding in of local shortages of salt supplies for people to grit their own areas.
Councils insist all gritting is the responsibility of Roads Service, but Roads Service said its gritting policy did not extend to footpaths.
Stormont health committee chairman Jim Wells said Roads Service was battling to keep on top of gritting roads but he couldn’t understand why councils haven’t been given the powers to grit pavements in an emergency situation.
“After the holiday period a lot of pensioners are out and about getting essential supplies and going to the post office, and unfortunately there is no salting on the pavements and they run the risk of slipping and ending up with a serious injury,” he said.
Traffic came to a standstill across Northern Ireland yesterday as snow and ice hampered traffic. There were reports of minor accidents around the Newtownards area while Mr Wells said tractors were digging out stricken cars on the Ballynahinch to Downpatrick Road.
A Roads Service spokeswoman said: “During periods of sub-zero temperatures and snow Roads Service resources are prioritised on ensuring the main road networks which caters for 80% of traffic are gritted and teams of workers have been tirelessly working day and night to ensure that these have been kept open.
“Roads Service is also replenishing rural grit piles and salt bins which have been placed at hills, bends or junctions for areas not on the main roads network. Roads Service policy does not extend to gritting footpaths.”