Watch: Video shows Nelson home plunged down cliff after 'devastating' rain

One person has reportedly had a lucky escape after wild weather tore apart a South Island home and sent a sleepout plunging down a steep slope.

Video footage shows the sleepout on Stansell Ave in Nelson lying in pieces more than 20m down the slope as more than 400 homes in the region have been evacuated due to river flooding and landslides.

Civil Defence controller Alec Louverdis said at an update this afternoon 411 homes have been evacuated, including 113 because of landslides last night.

It is understood the Stansell Ave sleepout came down in the early hours of Thursday morning.

Neighbour John van Gosliga said a tenant had been living in the sleepout up until two weeks ago, at which point they shifted into a nearby room on the same property.

They were in that nearby room when the sleepout plunged down the slope, van Gosliga said.

"If it happened two weeks ago, he would have been history."

The remains of a sleepout can be seen strewn across the bottom of a slope after tumbling away from a home during a landslide. Photo / George Heard

He said he had since helped the tenant move out of the property. No one else was home at the time of the slip.

Van Gosliga was confident his home had not been affected but said there were concerns another house, closer to the damaged home, had been undermined by the slip.

There were three homes further down the slope that could also be potentially impacted if other parts of the damaged property fell from above onto them, he said.

In fine weather, Stansell Ave is one of the most beautiful in Nelson, offering clifftop sea views.

However, van Gosliga said there had been drainage issues on the street and 11 years ago there was another big rain event that also caused a slip near the current one.

It comes as communities near Nelson have been evacuated for a second night as "devastating" wild weather continues to lash the top of the South Island.

Louverdis said it was unlikely people would be allowed back into their homes today.

He said he understood people's frustrations, but added the decision was made yesterday not to allow people back as they may have had to leave again as the bad weather returned yesterday.

A clifftop home in Nelson that normally offers sea views has instead been torn apart by a landslide that took place during a heavy downpour. Photo / George Heard

He estimated roughly about 1200 people could be displaced from their homes in Nelson tonight.

Louverdis said the damage he saw yesterday was "heartbreaking" and the city was "years" away from a recovery.

"As we were driving there were slips falling everywhere," Louverdis said, who was visibly emotional reflecting on the damage.

Nelson Mayor Rachel Reese said the damage was devastating and dramatic.

Projects in the city, for example, that had been worked on for years had been destroyed by rampant weather.

"It's a very tough situation," Reese said.

And there will be people who cannot return to their homes ever.