Damage to roads and the city's infrastructure will "take years, not months" to repair, says the mayor of Nelson city, devastated by floods in the Pacific nation.

New Zealand has been lashed by wild weather with the Nelson-Tasman district on the South Island bearing the maximum brunt.
New Zealand has been lashed by wild weather with the Nelson-Tasman district on the South Island bearing the maximum brunt. (AFP)

A New Zealand city devastated by flooding will take years to recover, the mayor has said, as hundreds more homes were evacuated.

Several streets in the city of Nelson were flooded after the local river, the Maitai, burst its banks.

Nelson Mayor Rachel Reese said on Friday the damage to roads and the city's infrastructure will "take years, not months" to repair.

She added that it was "critical" for Nelson's residents to conserve water as the city's supply was disrupted by a landslide that damaged the main line from the local reservoir.

The Pacific nation has been lashed by wild weather with the Nelson-Tasman district on the South Island bearing the brunt after 75 centimetres of rain reportedly fell over three days.

On a visit to witness the damage, New Zealand's Minister for Emergency Management Kieran McAnulty pledged $125,000 of aid and confirmed more than 400 homes have now been evacuated in Nelson, where a state of emergency remains in place.

He added that flooding and landslides have made 60 homes potentially uninhabitable.

McAnulty told reporters one of the most striking things he saw was a street on a housing development "where the road had just been washed out, (leaving) a crater deeper than I am tall".

Nelson resident Paul Maskell said a neighbour alerted him to the rising water on his street.

"By the time I got back, it was a foot deep in water with boulders running down the road. It was surreal," he told the New Zealand Herald.

READ MORE: Families flee as 'frightening' floods hit New Zealand

Homes without power

An elderly resident recovering after an operation had to be winched to safety by firefighters late on Thursday night after his home was threatened by flooding.

New Zealand's South Island was bracing for another lashing of heavy rain, but other regions did not escape the extreme weather.

The nearby city of New Plymouth endured its wettest August day since records began with 10 centimetres falling in 12 hours.

"More than a metre of rain has fallen causing significant flows down all rivers," said Taranaki Civil Defence controller Todd Velvin with flooding, road closures and fallen trees creating problems.

Kaitaia, a town near the top of North Island, was cut off by flooding and landslides, and around 400 homes were left without power in the far north.

Experts say the climate crisis driven by human activity is boosting the intensity and frequency of extreme weather events, such as heatwaves, droughts and flooding.

Source: AFP