Storms damage more than 100 homes in New Zealand

An unsettled weather pattern has brought a series of small tornadoes to New Zealand, damaging dozens of houses and hospitalising at least one.

Weather agency MetService reported more than 8800 lightning strikes across the country on Monday in a dramatic day of storms for both North and South Islands.

Tornadoes have been reported in three areas: the Tasman region at the top of South Island, on the Kapiti coast north of Wellington and in the eastern part of Auckland.

About 50 homes were impacted in Tasman, where Fire and Emergency NZ (FENZ) report roofs being dislodged, trees being uprooted and powerlines downed near Motueka and Upper Moutere.

Radio NZ reported a tree fell onto a car with a person inside, who received minor injuries.

In Auckland, 10 homes were yellow-stickered, rendering them unsafe to live in pending further assessment from extreme winds late on Sunday, among 51 reports of damaged homes.

Massive winds also struck Paraparaumu on the Kapiti coast early on Tuesday.

FENZ said four houses lost roofs and one was lifted off its base in the storm, with fences dislodged and power lines strewn about.

FENZ assistant commander Stephen Hudson said a teenager was in hospital for assessment after sleeping in "one small structure which which was completely destroyed".

There are concerns for further storms on Tuesday as a pattern of unsettled weather crosses NZ, with a particular risk to the Buller and Westland regions of South Island and the top half of North Island.

MetService meteorologist Alwyn Bakker said the organisation was reluctant to classify a storm as a tornado without pictorial evidence, but there was no doubt about their severity.

"We call them thunderstorms with tornadic wind gusts. We're being fussy scientists here," he told AAP.

"We're getting reports there have been some touchdowns ... and I've seen pictures of Titahi Bay (in northern Wellington) of a waterspout.

"There are definitely big dramatic thunderstorm clouds (and) when that is happening, there's a lot of wind associated with that, and big gusts."

Mr Bakker said "a big low pressure system lying over the South Island" was driving a very unstable northwesterly flow over much of the country.

NZ is no stranger to tornadoes, with up to 10 reported each year, though none of the severity seen in places like the United States.

The storm damage comes on top of two major events already this year - flooding in Auckland and Cyclone Gabrielle, which caused billions of dollars worth of damage.