WILD WEATHER LATEST:

• Flooding swamps parts of Auckland, large fallen tree blocks Māngere road
  • Buller Electricity is cut off from the national grid - leaving the region without power
  • A giant slip has closed State Highway 1 between Orewa and Puhoi
  • One person taken to hospital after falling tree causes crash in Kaitaia
  • Winds hit 135km/h in Whangārei, 100mm of rain in Kerikeri since midday yesterday
  • MetService warns of "significant event" in Bay of Plenty, Rotorua, Taupō and Coromandel

Roads across the upper North Island are submerged by flooding and blocked by slips and thousands have lost power as wild weather continues to lash 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 today.

Emergency services have just 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 with state highways in both islands are now impassable. Along with the road closure at Puhoi, SH25 is also closed between Wharekaho and Kuaotunu due to a slip.

A vehicle is stranded in rising floodwaters on Beachcroft Rd, Onehunga. Photo / Hayden Woodward

Snow is now falling on parts of the South Island with inland Canterbury and Otago highways either closed or under warnings.

A warning that the Auckland Harbour Bridge might have to close due to wind gusts was lifted mid morning though Waka Kotahi NZ Transport Agency said speed reductions might still be likely.

Several roads across the city are blocked by flooding including Beachcroft Rd in Onehunga Ihumatao Rd in Mangere.

Delay your journey

Waka Kotahi NZ Transport Agency 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.

State Highway 1 has been closed as the rain has brought down trees, rocks and mud. Photo / Facebook - Gary Vaughan

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.

Waka Kotahi is closely monitoring the weather, and is warning of potential closures to Auckland's Harbour Bridge.

MetService has issued a strong wind warning for Auckland from 2am until 9am today, with gusts of up to 110 km/h forecast to strike during the morning rush hour.

Waka Kotahi is warning Auckland motorists to avoid using the bridge over this time as wind speeds may surpass the threshold for safe use of the bridge, and could result in multiple closures over a one to two-hour time period.

"Motorists are urged to plan ahead as the predicted closures could coincide with peak morning traffic."

Drivers of high-sided vehicles and motorcyclists are encouraged to avoid the bridge while wind warnings are in place and use the Western Ring on State Highways 16 and 18.

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.