Weather: Sub-tropical low to drench north, snow for South Island

Rain alerts have been issued ahead of a wet weekend across New Zealand. Photo / Andrew Warner

A sub-tropical low packed with rain is bearing down on the top half of the North Island while flood-ravaged parts of the South Island are set for another round of intense downpours and a polar blast.

MetService has issued a fresh raft of heavy rain alerts for coming days, and warns some areas are under threat of flash flooding, slips and hazardous driving conditions.

The forecaster said Aucklanders could expect showers from Thursday, and across the weekend with the bulk of the rain expected to hit Northland, Coromandel and Gisborne.

A heavy rain watch has been issued for Mt Taranaki, Kapiti-Horowhenua, Marlborough, Nelson, Taranaki, Tararua, Wairarapa and Wellington.

🤦‍♂️ The sub-tropical jet stream is at it again...

🪄 In its next act, it will help spawn a sub-tropical low near the North Island this weekend 🌧️

Because the polar jet felt left out, it will come in behind & bring winter back to the South Island 🤷‍♂️ pic.twitter.com/JQiVVy66kj

— NIWA Weather (@NiwaWeather) September 27, 2022

Heavy rain warnings have also been put in place for the Westland and Buller Ranges and parts of the Tasman district with up to 180mm expected to fall in the Kahurangi National Park.

Those in the area are being warned to watch for rapidly rising streams and rivers.

The forecaster said a cold front would sweep up the South Island on Thursday, then over the central North Island on Friday. This would bring heavy rain and cooler temperatures to the west and north of the South Island.

Heavy Rain Watch issued for Kapiti-Horowhenua, Marlborough, Nelson, Taranaki, Tararua, Wairarapa, Wellington https://t.co/846WsVwNzM

— MetService Severe Weather Info (@MetServiceWARN) September 27, 2022

While the nation is experiencing relatively warm temperatures today, changes in the deep south tomorrow would see a dive to a wintry 0 degrees.

Metservice said there was potential for snowfall above 400m in Southland and Canterbury.

While Christchurch would enjoy a balmy 23C tomorrow, the mercury would plunge to a wintry 10C by day's end.

The latest round of wet weather comes just weeks after western regions of the upper South Island were inundated in by devastating floods last month.

Record-setting rainfall saw Nelson and Marlborough put into a state of emergency as rivers breached their banks and properties disappeared in floodwaters.

Homes around Nelson were evacuated with slips collapsing hillsides, and leaving properties ruined.