Weather: Farmers fear South Island storm will be 'deadly' for newborn lambs

As heavy and gale-force winds hit the South Island on Monday, farmers are saying this could be deadly for newborn lambs.

New Zealand has been hit by a 'weather bomb', bringing below-normal temperatures as an Antarctic blast sweeps the country.

Temperatures nationwide will drop and parts of the South Island will be more than 8C below average at times.

"Wind chills and temperatures this low will be deadly for newborn lambs and the coldest of the air arrives tonight and into Tuesday," WeatherWatch says.

Sheep farmer Chris Dagg is expecting 250 lambs in the next couple of days but says some may succumb to extreme cold.

"We've just to deal with it I guess," he told Newshub. "As long as the wind stays away, we'll make the best of a bad thing."

The Antarctic blast sweeping New Zealand has forced Invercargill Airport to shut.

Prime Minister Jacinda Ardern on Monday was forced to drive to Dunedin during her campaign trail after her scheduled departure out of Invercargill was cancelled.

Authorities in Queenstown are asking people to stay off the roads unless necessary and to check for snowfall warnings and closures before leaving.