More wild weather is in store for parts of New Zealand today as a Tasman Sea storm makes landfall, bringing sporadic downpours, gale-force winds and possible thunderstorms to western regions. 

The storm reached Fiordland this morning, and MetService issued staggered orange heavy rain warnings as it moves north, covering northern Taranaki and King Country, Buller and Grey districts, the headwaters of the Canterbury lakes and rivers, and Westland. 

Less severe yellow heavy rain watches are in place for Golden Bay, the Kāpiti Coast, northern and eastern Northland, the headwaters of the Otago lakes and rivers, and the Richmond, Bryant and Tararua Ranges, alongside a strong wind watch for the Canterbury high country. 

MetService meteorologist Braydon White told the Herald the low-pressure system was travelling eastwards from Tasmania and southern Australia, and would bring warmer-than-average April temperatures and significant rainfall as it moved north. 

“It’s going to start marching up the South Island today and then cross over into the North Island through tomorrow. 

“[The fronts] can be quite convective, so there may be a number of thunderstorms, and that could bring some squally gusts or localised heavy rain.” 

Rain and thunder modelling for New Zealand at 6am on Saturday, April 18. MetService warns the low-pressure system could bring up to 150mm of rainfall to some regions. Photo / Windy.com 

Today’s heavy rain warnings blanket much of the South Island’s West Coast, with areas closest to the Southern Alps expecting up to 150mm of rain. 

An orange-level warning is in place for the Westland ranges from noon today until 3am tomorrow, with a second issued for the headwaters of Canterbury lakes and rivers from 2pm until 6am. 

Heavy rain will reach the Buller and Grey districts by this evening, with a warning in effect from 5pm to 11am. 

Strong northwesterly winds with potentially severe gales are expected in the Canterbury high country, with a yellow-level wind watch in place from 2pm today for 15 hours. 

“It’ll be windy, but for places like Wellington and Canterbury high country, they’re not winds that are hugely unusual for those areas,” White said. 

Yellow-level rain watches in Golden Bay and the Richmond and Bryant Ranges cover 12 hours from 3am tomorrow, while the Kāpiti Coast and Tararua Ranges will be under one from 10am tomorrow until 2am on Sunday. 

An orange-level rain warning is in place for northern Taranaki and King Country from 11am tomorrow until 5am on Sunday, with MetService forecasting 80 to 110mm of rainfall. 

Eastern and northern parts of Northland will then fall under a heavy rain watch for eight hours from 9pm tomorrow, with patches of heavy rain and possible thunderstorms expected. 

While the system is expected to move through quickly, with most warnings only 12 to 18 hours long, already-saturated regions may struggle under a sudden downpour in a short period of time. 

“Some of the bigger concerns are for the North Island in areas that have already seen impacts previously this year,” White said. 

“As those fronts approach Northland late Saturday into early Sunday morning, we start to again see those convective risks and the chance of some localised downpours, which of course is the last thing that area needs.” 

People should take “sensible precautions” in areas expecting heavy rain, White said, given the risk of surface flooding and slips. 

“Rivers will rise quickly, so avoid crossing streams if you’re tramping. 

“And just be careful if you’re driving. If it’s really heavy rain, don’t drive through flood waters.”