A new severe thunderstorm warning has been issued for the bottom of the North Island, with the thunderstorms expected to be accompanied by torrential rain and damaging wind gusts.

MetService said the warning affects those in the following local government areas: Wellington City, Upper Hutt City, Hutt City, Porirua City, Kapiti Coast and South Wairarapa.

“At 8.30am, MetService weather radar detected severe thunderstorms near offshore Mana Island, Porirua and Pukerua Bay.

“These severe thunderstorms are moving towards the southeast, and are expected to lie near Wellington, offshore Mana Island, Porirua, Paekakariki and Pukerua Bay at 9am, and near Wellington, Lower Hutt, Upper Hutt, Porirua and Wainuiomata at 9.30am.

“These thunderstorms are expected to be accompanied by torrential rain and damaging wind gusts.”

MetService earlier warned a complex trough was set to pummel parts of New Zealand this weekend, bringing heavy rain, possible thunderstorms and gale-force winds.

Wellington drivers have already been told to avoid State Highway 59 at Mana, with the highway closed due to flooding, NZ Transport Agency said.

A string of severe weather watches and warnings is already in place for much of the country, with the risk of flash flooding in some areas.

An earlier severe thunderstorm warning for the lower North Island has been lifted, however a severe thunderstorm watch remains in place for Manawatu, Tararua, Kapiti-Horowhenua, Wairarapa and Wellington until 1pm today.

“A very active line of thunderstorms lies over northern Wellington and southern Kapiti, extending eastwards into Wairarapa. This line is moving slowly northeastwards, accompanied by very heavy rain, possibly torrential in places”, MetService said in a statement.

“People are urged to stay alert to these severe weather conditions, with flash flooding likely.”

MetService meteorologist Braydon White told the Herald a front had pushed its way up the South Island overnight and was set to gradually move over the North Island today.

White said Gisborne was one of only a few North Island regions expected to escape the wet weather until Sunday.

“Most people will be wet in the North Island [today], although in some places like Auckland it’d mostly be in the second half of the day and into the evening,” White said.

This rain could put a damper on Auckland’s sports-packed weekend, potentially affecting the One New Zealand Warriors’ clash with the Gold Coast Titans at Go Media Stadium in Penrose.

MetService has warned that a complex trough is set to pummel parts of New Zealand this weekend. Image / Windy.com 

He said that alongside the rain, MetService was expecting “pretty squally thunderstorms in western areas”.

The main concern was heavy rain over short periods for localised areas.

“Unfortunately, that includes northern and eastern parts of Northland, which as we know [has] already had so much rain this year. This isn’t something that they want.”

He said MetService was not expecting this weekend’s weather to be as severe or as impactful as previous events, such as Cyclone Vaianu, but the risk of flash flooding remained.

Temperatures would be “a touch warmer” than average for this time of year, White said.

“We’re seeing low temperatures of around the mid-teens for most places. Further south [they’re] still getting some single digits, though.”

Severe weather watches and warnings 

An orange heavy rain warning is in place for Taranaki north of about Eltham and King Country from 11am today until 5am tomorrow.

The same warning is in place for the Buller and the Grey districts until 11am.

The headwaters of the Canterbury lakes and rivers are under the same rain warning until 6am.

A heavy rain watch is in place for the northern and eastern parts of Northland, north of Whangārei, from 9pm until 5am tomorrow.

Tasman northwest of Motueka is also under the same watch until 3pm.

The Tararua Range, the Kāpiti coast and parts of Wellington north of Porirua are under the same heavy rain watch until 2am tomorrow.

The Richmond and Bryant Ranges are under the same watch until 3pm.

Wild weather next week 

On Sunday, a “very large area of low pressure” would sit over the top of the country, White said.

“Because of that, we have a number of spiral bands of rain that kind of wrap around the low and just bring periods of rain or showers to much of the country through Sunday and into Monday.”

At the start of next week, the rain bands were expected to shift eastwards.

“Those bands, instead of passing over, they start becoming slow-moving. And that is potentially going to bring some persistent and possibly significant rain.”

He said at this stage it was still uncertain where the rain would fall, though the eastern South Island appeared most likely to be wet through the beginning of next week.