In pictures: Wild weather wreaks havoc across Wellington Region

Hail, heavy rain and strong winds ripped across the country from Canterbury to Wellington on Tuesday, taking roofs, powerlines and trees with them.

Broken windows, tree debris and metal roof panels were seen strewn across the roads in central Lower Hutt in the aftermath of the storm.

Fire and Emergency said they responded to more than 60 weather-related call outs with many in Lower Hutt CBD.

Police said they responded to reports of extensive damage to the roof of a property on Cornwall Street about 4pm, where there was a strong smell of gas. The road was blocked.

People in Lower Hutt were rushing to clean up their homes, board up any damaged windows and tie down any loose debris before the sun went down.

By 8pm, about 330 properties in Days Bay and Waterloo were still without power - down from about 2000 across Hutt Valley.

Wellington Electricity's website states the outage cause for Waterloo was unknown and that they were working to restore power as quickly and safely as possible.

The Days Bay outage was caused by the adverse weather damaging equipment, the provider said.

Lower Hutt Mayor Campbell Barry said there had been extensive damage from strong winds during the thunderstorm.

"We've had some roofs in our commercial area be ripped off and also some damage to garages and homes.

He said the council was working alongside Fire and Emergency to do welfare checks and ensure people got the support they needed.

He was aware of a small number of people who would not be able to return home on Tuesday night due to the damage.

A person, who wished to not be identified, said strong winds like a "tornado" inside the atrium of Bunnings in Petone caused chaos.

One of the air vents was ripped off the roof and a small amount of the store's stock had been damaged.

An electrician working on a construction site in Lower Hutt also said the strong winds were like a tornado that whipped up all the materials on the site.

He said he was working inside a warehouse when he noticed it getting darker.

"Then all of a sudden all the rubbish started blowing upwards from our skip bin and blowing up all the sheet metal."

He described it as very loud and pretty frightening but said luckily there was no damage on site.

MetService said while eyewitnesses described a "tornado" ripping through Lower Hutt on Monday afternoon, it was more likely to be extremely strong winds.

Meteorologist John Law said tornadoes were difficult to spot on radars, and MetService relied on pictures of the "funnel cloud" to officially categorise them.

But the Wellington region had certainly been battered, he said - describing an "unsettled story" for the eastern side of the motu.

There had been about 180 lightning strikes, wind gusts of up to 100km/h, intense bursts of rain, and "fairly large" hail stones up to 15mm in diameter, which covered large parts of the region.

Lighting Direct on Knights Road was seriously damaged by the storm. The front doors and windows have been pulled away from their frames, taking part of the storefront with it.

The winds also blew out some of the windows of an almost-empty school bus in Lower Hutt - route 888 bound for Eastbourne.

Metlink Senior Manager operations and partnerships Matthew Chote said two adult passengers who were on the bus are safe and unharmed. There were no school students on board."

The National MP for Hutt South, Chris Bishop's office has also been hit - with part of the building having had its roof torn off so there is now a gaping hole into the top floor.

Large windows in the front of Hutt City New World in Lower Hutt were ripped out by the winds, sending glass flying across the road.

Shopper Anna arrived at the New World in Lower Hutt's Queensgate mall to find the supermarket damaged.

"There's a huge window been completely smashed, there's glass all over the road and the organic shop next door [has] also got glass all out the front of it and its had a window knocked out - all its fences are flat on the ground."

Commonsense Organics just down Waterloo Road has also lost a window, glass screens and a fence to the strong gusts.

The Salvation Army family store in Hutt City had its windows blown out the front of the shop. Contractors have boarded up the holes.

Parts of a small mall in the Wellington suburb of Karori also flooded during the wild weather in the capital.

Countdown supermarket and Unichem pharmacy were forced to close early.

The pharmacy posted on its Facebook page that the dispensary ceiling had flooded, and there was water damage in its consultation room.

It said it would open on Wednesday morning, but people should expect delays with prescriptions being processed because computers were also damaged.

"There is still a lot of water which is being dried out around the inside of the pharmacy with large industrial fans, this will be going all day tomorrow so might be noisy instore," it said.

Ominous clouds were seen going across Tītahi Bay, Porirua.

In Christchurch, Fire and Emergency New Zealand said heavy rain flooded houses in the suburbs of Belfast and Middleton.

Several flights were cancelled and delayed at Christchurch Airport.

Airways New Zealand said lightning strikes affected some of the "critical infrastructure" which affected some flights temporarily.

The Gisborne region was hit later on Tuesday evening, with Uawa Civil Defence - Tolaga Bay East Coast posting on Facebook: "The thunderstorm has just hit Gisborne. Pretty spectacular".

MetService said at 9pm the storm was "weakening and moving offshore".