A cold blast of air from the Antarctic is bringing sub-zero temperatures and snow down to sea level in some parts of New Zealand.
Huge waves of up to eight metres are also forecast for the west coasts of both the North and South Islands this weekend.
Boaties and anyone keen on fishing from the rocks are being told to stay home until at least Tuesday because conditions are too dangerous.
"For the first time in a long time we've got good southerlies over the country, bringing cold temperatures from the South Pole," MetService forecaster Tom Adams said.
"They are already bringing cold temperatures and it will stay cold for a couple of days," he said.
Mt Cook fell to -3C last night, Blenheim was -1C and Waiouru in the central North Island was 1C. Nowhere got out of single digit temperatures.
But windy conditions have prevented it getting any colder. As skies clear over the weekend, temperatures will fall even further.
The coldest spot will be Alexandra, where the temperature is likely to drop to -5C overnight tonight and -6C tomorrow night. Wanaka is looking at -3C and -5C, and Queenstown -4C both nights.
"Those places are a bit more sheltered from the southwesterly winds, not being on the coast, so it's going to be pretty cold. Alexandra is only looking at 4C as a daytime maximum," Adams said.
Dunedin stays above 0degC, just, with predicted overnight weekend temperatures of 3C and 2C.
Most southern highways are open on Saturday morning; however, the Milford road (State Highway 94) is closed owing to snow and there are cautions in place for other highways. Further north, the Lewis Pass (SH7) is also closed.
Southland and Otago farmers should be wary of the "brutal wind chill" that could prove dangerous to newborn lambs and calves by pushing localised temperatures well below zero, WeatherWatch head analyst Philip Duncan said.
A couple of fronts would bring snow showers over the next two days. Metservice's severe weather outlook warns of likely snow for the central North Island and the north-west and far south of the South Island. Snow could get down to sea level in parts of Southland tomorrow.
"The snow will be good for skifields in the Southern Lakes, and Mt Ruapehu," Adams said, though he warned that there was a risk of gales for the bottom of the South Island on Monday.
A "big pulse of swell" will produce waves up to eight metres on the West Coast of the South Island and the west coast of the North Island south of Kaipara Harbour. Further north, swells would be around six metres.
MetService is also warning of severe southwest gales for parts of Southland, Clutha and Dunedin on Monday and early Tuesday.
