Weather: Band of thunder blasting over New Zealand, much of country 'at risk of a lightning display'

A band of thunder will blast over the North Island on Tuesday with MetService warning much of the country is at risk of a lightning display.

Earlier today a front moved through Wellington and Kapiti Coast bringing wild winds, flooding and slips and derailing a train.

Now its northern areas' turn to be hit, with strong to gale-force nor'westers followed by the thundery front.

WeatherWatch warns gale-force gusts are most likely in exposed places, including some parts of Auckland City - and a strong wind warning has been issued for Auckland's Harbour Bridge.

MetService says the severe weather warnings for northerly gales have been extended until 3pm on Tuesday. The New Zealand Transport Agency has issued strong wind warnings for the Harbour Bridge.

"There is currently a strong wind warning in place over the Harbour Bridge. Please take extra care if you are travelling on this route, especially if you are in a high-sided vehicle or riding a motorcycle," it tweeted.

These powerful winds will be followed by the risk of thunderstorms, although large areas will just get heavy downpours and no thunder.

"There is also a moderate risk of thunderstorms about western Northland and Auckland this afternoon and early evening, and also about the eastern Bay of Plenty ranges tonight," MetService warns.

"These thunderstorms will bring localised heavy rain, small hail, and strong squally northwesterly wind.

"From Taranaki to Wellington however, the thunderstorms late morning and early afternoon will be embedded in a very strong northwest flow, and there is a low risk of damaging wind gusts in excess of 110 km/h."

Western parts of the South Island remain under a moderate threat of thunderstorms all day, while there's also a moderate risk of a few thunderstorms about inland parts of Southland, eastern Otago and South Canterbury this afternoon and evening, and mid-Canterbury and Banks Peninsula tonight.