Thunderstorms blow over after sweeping large parts of the North Island

Emergency services say the thunderstorms sweeping large parts of the North Island have blown over.

MetService has lifted all its severe thunderstom watches and warnings for the area.

Fire and emergency say there were some lightning strikes today, which caused minor damage to some buildings.

They say most weather-related call outs were from alarm activations, and there there were no known threats to life.

Red warnings were in place north of Auckland and south of Hamilton, where thunderstorms were strongest this afternoon.

There are reports of a roof collapsing at a house in Wairau Valley and a flooded house in Totara Vale in Auckland after this afternoon's brief storm.

Auckland Emergency Management said the Mahurangi River has flooded at Falls Road near Warkworth.

It was urging motorists to avoid taking Falls Road, especially sections that ford the river. A man was killed in January after his car was swept away at the same crossing.

Fire and Emergency NZ said they had been called to "a couple" of weather-related calls across Auckland by 5.30pm, including a roof collapse and flooding inside a house.

Both were in Auckland's Wairau Valley on the North Shore, the spokesperson said, and one fire truck had been sent to each.

The severe thunderstorms are moving towards the southeast.

Much of Auckland was drenched in heavy rain and hail late this afternoon.

In Auckland's Grey Lynn between Elgin and Northland streets, a billboard came down in strong winds. It knocked over fencing and was lying across the footpath and cycle lane and onto the road.

Send your pictures and video of any storm damage in your area to iwitness@rnz.co.nz

In Blenheim, part of the roof outside the Cotton On store in Blenheim collapsed because of rain build up. No one was injured and the shop has reopened to customers.

Metservice meteorologist Devlin Linden said today's severe weather had struck the North Island and parts of the South.

"Quite a lot of activity along much of the western North Island, right the way from Auckland down to Taranaki and that western flank, but there is also a good amount of activity in other places around the country.

"These storms are convective storms and are driven by heat thoughout the day. It's expected they're likely to continue though to early this evening, when things start to cool down" says Mr Linden.

Overnight Friday, MetService recorded nearly 2000 lightning strikes throughout the top of the North Island, as well as heavy rainfall, with downpours reaching 33.5mm an hour in the Bay of Plenty.

About 1845 lightning strikes were recorded from midnight.