Roads across the top of the South Island are now submerged by flooding and blocked by slips and thousands have lost power as wild weather lashes the country.
A massive slip has closed State Highway 1 north of Auckland as a fierce storm packed with hurricane-strength winds and torrential rain sweeps across New Zealand.
The sun is now reappearing in the north, but the wild weather continues to batter southern regions, where heavy rain, strong winds and snow is falling.
Emergency services have airlifted to safety a group of trampers who were trapped by a surging river near the base of the Tuahu track in the Manawaru area in the Waikato.
A police spokesperson said the trio were winched out by rescue helicopter this morning and were now undergoing a medical assessment.
And the wind and rain battering Auckland have brought down a large tree in Māngere.
Virtually every region is under a weather alert, with powerful winds wreaking havoc, causing trees and powerlines to topple, with at least one motorist injured overnight in Northland.
Driving conditions remain treacherous and some state highways in both islands are impassable. Along with the road closure at Puhoi, SH25 is also closed between Wharekaho and Kuaotunu due to a slip.
On the West Coast, debris and downed powerlines have closed highways. Motorists are urged to delay travel.
MetService is warning of a "significant event" unfolding in the south, with a further 30cm of snow to fall in some inland parts in coming hours.
A warning that the Auckland Harbour Bridge might have to close due to wind gusts was lifted mid morning, but a fresh warning was issued this afternoon, saying lanes may close the bridge as wind gusts start to rise.
Waka Kotahi NZTA said strengthening wind mean reduced speed limits were now in place on the bridge and lane reductions may start be required.
Several roads across the city are blocked by flooding including Beachcroft Rd in Onehunga Ihumatao Rd in Mangere.
Delay your journey
Waka Kotahi said due to a "large slip and fallen trees" the motorway was closed between Orewa and Warkworth.
"Motorists are advised to delay their journey if possible, or be prepared for a long detour via SH16," the transport agency said.
Video posted to social media shows a large cliff-face appears to have fallen, with the road strewn with rocks and mud.
Commuters were earlier warned to delay their drive this morning as the strongest rain and heaviest gales were likely to hit just as people were trying to get to work.
The entire country is dealing with rough weather, with a month's worth of rain predicted today in parts of North Island and northern and eastern parts of the South Island.
Rain is falling across most of the country between Auckland and Christchurch, as a deep low and associated rain-bearing front move down the North Island, to encompass the whole country.
Severe weather warnings have been issued for most of the North Island and much of the south.
Auckland Transport was warning of disruptions to bus services on the North Express and on services from Glenfield, Beach Haven and Takapuna.
Ferry passengers are also being told to expect potential disruptions and are asked to delay their travel if possible.
"On windy and choppy days like tomorrow ... our ferry operators often cancel trips or replace them by road depending on the conditions."
The harsh weather is the result of a deep low moving across New Zealand, bringing with it associated fronts which cause the conditions.
Between Coromandel and Bay of Plenty, people can expect winds approaching gale-force and up to 110mm of rain, with rates of 15mm per hour at times.
Heavy rain means flooding is likely for much of the Waikato region where catchments are already saturated. River flooding along low-lying coastal areas may also be exacerbated over high tide periods for all Waikato region coasts.
The regional council has asked residents to stay vigilant for localised flooding and slips caused by the high river and stream levels.
Gisborne to Hawke's Bay can expect similar conditions, with heavy rain, while Wellington will get gale-force winds until at least tomorrow morning. The Tararua Ranges will get a deluge and Nelson and Marlborough can also expect heavy rain and wind.
A heavy snow and rain watch are also in place for Canterbury's high country, Central Otago and the Lakes district.
The wintry blast is being attributed to an "atmospheric river" snaking across the country. These long, thin filaments of atmospheric moisture are capable of carrying double the average flow of the Amazon River – or 200 times that of our largest river, the Clutha/Mata Au.
Around 40 atmospheric rivers make landfall here every year, with four or five classified as strong and usually hitting around summer.
