Wild winds have brought down powerlines and trees in and around the Wellington region, while a mammoth 11m wave has been recorded off the South Island coast.
The treacherous winds and seas come as New Zealand wake to freezing temperatures, with snow falling to low levels in the North Island - forcing the closure of State Highway 1, the Desert Rd, through the Central Plateau.
It was -1C in Hamilton and 0C in Waiouru early today while towns like Taupo and Taihape were also barely raising the mercury. All major cities, including Auckland, were struggling in single numbers - with Auckland as low as 3.4C overnight.
As well as the closure of the Desert Rd, other roads are also dicey: snow has been falling on the Napier-Taupo Rd, on the Remutaka Hill Rd north of Wellington and on Lewis Pass in the South Island.
The MetService said snow was likely to affect the Desert Rd until 1pm today.
Heavy snowfall warnings have also been issued for Taihape, the Ruahine Range and the Tararua Range.
One truck driver told Newstalk ZB he'd faced treacherous conditions, heading south towards Taihape, through the night.
Strong gusts of up to 120km/h in and around Wellington are expected until late this morning, weather experts say.
A monster wave measuring 11.82m high was recorded east of Banks Peninsula, Niwa said just after 6.30am. And a maximum wave height of 7.49m was recorded at Baring Head.
A strong wind warning was issued by MetService last night, when locals were warned to tie down rubbish bins and trampolines as "severe southerly gales" were forecast in exposed places.
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Central northern fire communications said they were called out to four weather-related incidents overnight and in the early hours of this morning.
Fire crews went out to Nelson St, in Naenae, Lower Hutt, shortly before 5am today, where powerlines had come down.
The same thing happened just after 3am in Avalon, where a tree was blown onto powerlines, also bringing them down.
A spokeswoman said they were also called out to the suburb of Seatoun, where plastic roofing sheets had come loose at a property there.
Police were called to Moa Point, after a report of rocks on the road.
A MetService spokesman said gusts of between 120km/h to 125km/h had been recorded in the Wellington region overnight - but was expected to ease back from late this morning.
"We're on a very gradual easing trend now for much of the morning and for the rest of the day, really, we're not going to see much significant weather," he said.
A high-pressure weather system is gradually coming over the country from the west and the northwest, which will bring finer weather and more settled weather for many parts of New Zealand from today and through to tomorrow.
Monster waves had also been sighted on the coast and MetService said the largest wave measured by a wave buoy overnight was 6m high - which he described as a "very large wave".
"The main thing now is just that we're on a very gradual easing trend for the first half of the day and the second half of the day, things will ease quite quickly away," he said.
MetService has issued a number of severe weather warnings and watches in and around the country.
It has warned of severe southwesterly gales for Wellington, southern Wairarapa, northern Hawke's Bay and Gisborne this morning.
There is also a warning of heavy snowfall over Taihape, in the Rangitīkei District, the Ruahine Range and the Tararua Range.
Winter woollies will be much-needed this morning in many parts of the country, where temperatures just before 7am ranged from -1C in Hamilton to 11C in Kaitaia.
Aucklanders woke up to a chilly 4.8C.
However, it will be a fine day in the City of Sails - save for showers early in the morning. A high of 13C is forecast in Auckland.
The coldest place to be at that time was in Twizel, where it was -5.7C, while the warmest part of the country was in Kaitaia, at 10.8C.
Heavy snowfall warnings, Desert Rd closed
Road snowfall warnings are also in place.
Motorists planning to use the Desert Rd are being told to stay away as it is closed due to heavy snow; while road snow warnings have been issued for Napier-Taupō Rd, Remutaka Hill Rd and Lewis Pass.
On Desert Rd, snow is expected to affect it until about 1pm today. Between 20cm to 25cm of snow could accumulate above 800m there, with lesser amounts to 500m, MetService said.
A truck driver out early this morning described slippery and "shocking" conditions.
"This is slippery - absolutely shocking. I'm leaving Waiōuru and doing 24km per hour. There's about of us in line and we're all creeping along," he said.
The driver, who wanted to be known only as Allan told Newstalk ZB early this morning that he had detoured around the Desert Rd before rejoining State Highway 1 at Waiōuru.
"The snow's right down. It's coming down really heavy. When it snows, it's warm. But when it stops snowing - that's when it cools down."
- Auckland: 13C temperature high, 6C overnight low. Fine spells, showers becoming isolated this morning and clearing this afternoon.
- Kaitaia: 15C, 6C. Fine spells. The odd shower, mainly in the morning. Southwesterlies.
- Whāngārei: 14C, 5C. Fine spells, the odd shower, mainly in the morning.
- Hamilton: 11C, 0C. Fine with a frosty start. Southwesterlies.
- Tauranga: 13C, 3C. Mainly fine with early frosts possible. Southwesterlies.
- Gisborne: 11C, 6C. Showers developing in the morning, possibly heavy, easing in the evening. Strong, gusty southerlies.
- Palmerston North: 10C, 3C. Showers clearing in the morning to fine spells. Gusty southwesterlies, easing in the afternoon.
- Wellington: 9C, 6C. Showers, easing in the afternoon. Severe gale southerlies, gusting 120km/ in exposed places, gradually easing.
- Nelson: 12C, -1C. Fine with early frosts. Southwesterlies dying out in the afternoon.
- Christchurch: 8C, -1C. Showers gradually easing and becoming confined to Banks Peninsula by evening. Southwesterlies strong at first.
- Queenstown: 8C, -3C. Morning cloud then fine. Southerlies dying out.
- Dunedin: 9C, 4C. A few showers, clearing in the afternoon. Southerlies gradually dying out.
- Invercargill: 9C, -3C. Some morning fog and one or two showers, then becoming fine in the evening. Light winds.