One person has been hurt after a tornado tore through New Plymouth this morning.
Residents in the suburb of Bell Block said they saw sheets of iron flying through the streets.
A vehicle was also struck by a trampoline.
A police spokeswoman said there were no reports of injury "but the person is a little shook up as you can imagine".
A spokesman for NZ Fire and Emergency said they were called to Paraite Rd after reports that a tornado had hit a building. One person suffered moderate injuries as a result.
Firefighters were also sent to a house in Henwood Rd after part of a roof was ripped off the building.
Niwa said just before 10.30am that over 400 lightning strikes had been reported across Taranaki and Waikato in one hour.
There are also reports of powerlines down in parts of the city. Electricity is out to more than 800 properties in the area.
Police and emergency crews have been called to State Highway 3 after reports a car had been hit by a trampoline near the Golf Course Lane.
Police started to get reports of a tornado in the area at 9.30am, the spokeswoman said.
SEVERE THUNDERSTORM WATCH:
for Northland, Auckland, Great Barrier Island, Coromandel Peninsula, Waikato, Waitomo, Taumarunui and Taranaki.
A situation statement said the threat period was between 9.30am today and midnight and during which would bring an unstable northwest flow that would result in squally thunderstorms to western areas.
"There is a chance some of the thunderstorms may become severe - bringing damaging wind gusts of 110km/hr or stronger [mainly near the coast], with a few small tornadoes also possible.
"The risk covers Taranaki to Waikato this morning through to this evening and for Auckland, western Coromandel Peninsula and Northland from this afternoon through to tonight.
"Wind gusts of this strength can cause some structural damage, including trees and power lines, and may make driving hazardous. If any tornadoes occur, they will only affect very localised areas."
Emergency crews were also out at Pohutukawa Place, in New Plymouth.
There have been no reports at that location also, the spokeswoman said.
Weather conditions in New Plymouth today include showers - some heavy with squally thunderstorms and hail.
Northwesterly winds are also forecast and a high of 14C is on the cards.