Portstewart Strand bore the brunt of heavy rain and gale force winds of up to 70mph on Monday – with many areas also affected by up to 10cm of snow.
A massive storm surge pounded the north coast, with the level of the beach dramatically dropping by a metre as the waves washed sand out to sea.
The blizzard conditions prompted weather experts to extend a yellow warning from midnight until 9am on Tuesday morning with challenging driving predicted.
Temperatures fell to -1C across the province with heavy rain throughout the night.
In Co Down, the Belfast to Bangor Road was closed while a fallen tree was cleared.
The Garvaghy Church Road in Dromore was also closed due to a fallen powerline.
Snow was reported across the province.
Dramatic images captured on Monday show waves sweeping into the dunes neighbouring Portstewart Strand and sweeping away waste bins and lifebelt posts. The National Trust's Toby Edwards, who manages the famous beach, said a storm surge had been exacerbated by high tide which arrived around noon.
"There is a massive storm out to sea and it's creating a big storm surge on the beach," he said. "Midday was high tide and it was pushing up pretty high, right up to the dune system and way higher than it would be on a calm day. There would be a big draining out of the waters and then it was pushing right back up the road. Everyone was having to run up to the dunes every now and then."
National Trust staff are now preparing for a clean-up.
"There has been significant sand movement which has dropped the overall sand level on the beach by about a metre. This will have been drawn further out to sea, although this is all part of the natural annual sediment movement," Mr Edwards said.
"Our local beach users were dashing up and down the dunes to escape the foamy waves and it was definitely a 'no go' zone for cars," Mr Edwards said.
The trust had issued online warnings.
The exceptionally high tide has also wreaked some damage on the dune's ecosystem.
The sand dune system which runs the entire length of Portstewart Strand covers nearly 1.5km with dunes rising to nearly 30m. It is an ancient dune system and an area of special scientific interest. It is one of very few places where environmental changes in the dunes and estuarine environment have been recorded over a 6,000-year period. The River Bann once flowed out into the Atlantic at the near end of the beach.