Air New Zealand said it had cancelled all flights to and from the capital Wellington, where wind gusts of 200 kilometres per hour were recorded when the storm moved in late yesterday.
The airline said services had also been suspended at Dunedin in the South Island, adding: "There are delays across the Air New Zealand network due to the weather conditions across the country."
A thick blanket of snow covered parts of the South Island, making alpine roads impassable and cutting off some communities.
"The wind was just roaring all night, it felt like the house was going to blow away," Wellington resident Kylie Goodman said.
Emergency services said they had received about 1,000 calls for help, while police urged motorists to exercise extreme caution until an expected break in the weather forecast today.