A storm set to blast much of the country over the next three days with wind, waves, hail and snow was born from an unusual and powerful mix of weather systems.
Civil Defence is urging people across the country, particularly those in the South Island and central North Island, to prepare for power and phone cuts in the worst storm of the winter so far.
"It's going to be cold - and it's going to be a significant storm system," MetService media and communications meteorologist Daniel Corbett said yesterday.
While it was unlikely Auckland would see a repeat of its snowfall two years ago, city residents would not escape the storm.
"To give you an idea, the temperature on Friday will barely get above 10C - so they are certainly going to be feeling the effects of the cold," Mr Corbett said.
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The storm will be a product of forces from Antarctica, the Southern Ocean and the north and south Tasman Sea.
The strong southerly change will begin working up the South Island today and is expected to reach the Far North by tomorrow.
Another deepening low to the east of central New Zealand will generate south or southwesterly winds up to severe gales around many exposed coasts.
"Those gales will reach all the way up towards the west coast and Waikato to Northland, but will slowly ease out as the pressure gradient opens as we go into Saturday and Sunday," Mr Corbett said.
There could be significant snow in parts of Canterbury, including Christchurch, and in Marlborough.
Powerful westerlies from Northland to Taranaki, accompanied by squally showers, had the potential to create high wind gusts tomorrow, he said, while large waves were also expected on many beaches.
Independent forecaster Weatherwatch expected hurricane-force southerlies with possible gusts of up to 150km/h from Kaikoura to Wellington and southern Wairarapa tomorrow night.
The storm is forecast to slowly ease by the weekend, leaving cold frosty nights in its wake.
RED CROSS ACTION
The Red Cross has set up an emergency operation centre in Christchurch and an incident management team will be in place from 10am.
Emergency response teams around the country are on standby to assist.
South Island emergency management officer Stephen Manson said they want to be in a position to respond to emergency community needs as they arise.
He said contingencies are being put in place to ensure weather conditions don't stop the delivery of Meals on Wheels.
Logistics support staff and extra equipment arrived from Wellington last night to assist the South Island crews.
Snow: Southern and eastern parts of the South Island, with snow near sea level and significant snowfalls about central and northern Canterbury. Snow is also expected about the Central Plateau and possibly to lower levels southwards to Wellington.
Wind: Strong south to southwest winds spread over the North Island tomorrow and Friday, with gales, possibly severe for a time about Wellington, coastal Marlborough, northern Westland and Wairarapa. Strong, cold, blustery westerlies are expected from Waikato to Northland, with gusty conditions also about the Bay of Plenty.
Rain: Cold rain is expected about southern and eastern parts of the North Island.
- NZ Herald and Newstalk ZB