Weather: More thunderstorms on the way for much of country, heavy rain watch issued

More thunderstorms are on the way after a relentless week of thunder and lightning.

MetService is predicting thunderstorms for much of the country on Thursday and has issued a heavy rain watch for Tararua. 

MetService is reporting all of the North Island has a chance of thunder on Thursday. These thunderstorms may produce brief heavy rain and small hail, strong wind gusts of up to 100 km/h, and a slight chance of small coastal tornadoes, MetService said.

For the South Island, there is a risk of thunderstorms in Buller, northern Westland, the Canterbury Plains, eastern Otago, and Southland. These storms could produce brief heavy rain and hail.

A heavy rain watch is in place for the Tararua Range until early Friday morning with periods of heavy rain and thunderstorms possible.

A heavy swell warning has been issued for Kapiti-Porirua Coast and Otaki to Cape Terawhiti until Thursday 6pm with waves expected to reach four metres.

It may be a wet day for much of the country but temperatures are in the 20s for most of the east coast.

Napier is expected to see a high of  23 degrees with Whangārei not far behind at 22 degrees, followed by Kaikōura and Gisborne which could hit 21 degrees.

Friday's forecast

The North Island is forecasted to have showers which will become isolated later in the day with long fine spells developing. The South Island is expected to be partly cloudy with isolated showers which will be more widespread in the south and west. 

Periods of rain are expected to ease in the Chatham Islands on Friday with northwesterlies turning southwest.