Trail of destruction left by tornado

Eight houses were damaged by this morning's tornado in Rahotu, three of them severely.

People in need can get help by going to Rahotu School.

There are 12,000 houses without power across South Taranaki. 

Taranaki Civil Defence this afternoon was warning of wind gusts of up to 120km/hour between 3pm and 11pm tonight.

Ripped-off roofs and downed trees and powerlines left by the storm have served another dramatic reminder that tornadoes can strike New Zealand - and hard.

But they're still very uncommon: on average, about seven to 10 moderate to strong tornado events are reported each year.

Because they're extremely localised, the damage they cause is very confined to the tornado itself, although the violent winds can fling debris hundreds of metres.

Roads closed, speed limits in place

Speed restrictions are in place on Auckland's Harbour Bridge, due to "significant" wind gusts.

Ferries are also cancelled from Northcote Point wharf, which is closed until further notice.

Buses were operating between Birkenhead and Northcote Point from 4.20pm to 6.50pm.

Police and fire crews are on the ground in the central North Island and on the West Coast of the South Island assisting those affected by heavy rain and winds.

A number of roads are affected by surface flooding and trees and power lines have been brought down.

SH6 is closed between the townships of Ross and Franz Josef Glacier due to trees which have been brought down at Pukekura.

In a statement, police said they are not aware of any weather-related injuries.

Motorists were being asked to follow the directions of emergency services and roading contractors around local road closures.

Non-essential travel should be delayed and motorists are being asked to take extra care.