Wellington - What weather forecasters warned would be "no ordinary storm" hit New Zealand on Saturday, bringing down power lines, toppling trees and ripping roofs from houses as torrential rains flooded the Northland region.

Winds gusting to 165 kilometres an hour were recorded at Cape Brett in the Bay of Islands and officials warned people to leave the centre of Whangarei, the region's biggest city with a population of about 50,000, as floodwaters swollen by high tides threatened.

As the storm moved south towards New Zealand's biggest city, Auckland, the MetService warned it was a "potentially destructive and dangerous storm" which could be the worst to hit the country for a decade.

Civil defence staff were on watch as power was cut to more than 1,000 homes and roads were blocked by floods and landslides, according to news reports.

MetService forecaster Andy Downs advised people in the North Island, especially from the Waikato province northwards, to avoid unnecessary travel.

But further south, the storm had already hit skifields on Mount Ruapheu, at 2,797-metres the island's biggest mountain, and Radio New Zealand reported that up to 10,000 skiers were being evacuated from the slopes.

The MetService predicted the storm would last about 24 hours and affect most of the North Island down to the capital Wellington, 1,100 kilometres south of the northernmost point, Cape Reinga. (dpa)