Flooding on the Coromandel Peninsula at the start of June.

Flooding on the Coromandel Peninsula at the start of June.
There have been thousands of lightning strikes off the top of the North Island.

Niwa Weather said there were 7347 lightning strikes in the Tasman Sea west of the country by about 3.30pm Wednesday.

Shortly after 7pm, MetService forecaster Sonja Farmer said most lightning was still to the west of Northland although there had been at least one strike in the Far North around the Karikari Peninsula.

"Most of the lightning at the moment is offshore but everything is sinking down over the country, so that all should get closer," she said.

Heavy rain was also falling in parts of Northland on Wednesday evening, with Kaikohe recording 12mm in an hour and Kerikeri 10mm.

"The rain is all over the place. The main block of rain cloud is over Northland and Auckland at the moment and it's sweeping around in a clockwise direction," Farmer said.

MetService has warned of a risk of severe thunderstorms in Northland and Auckland late this on Wednesday, and for Coromandel Peninsula overnight and Thursday morning.

A front was moving slowly south, and rainfall rates could get up to 40mm an hour.

There was also a risk of severe easterly gales overnight in Auckland, and from Wednesday night through to Thursday afternoon in Coromandel Peninsula, and northern Waikato and Bay of Plenty.