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Meanwhile, a powerful cold front threatens to bring a “dramatic temperature drop” and even lowland snow later in the week.

But before the cold southerly follows the low by bringing freezing weather to the lower South Island from late tonight, muggy conditions in the North Island could fuel thunderstorms and downpours.

Temperatures were ranging from 22C in Napier today and 6C in Invercargill today, according to a Niwa Weather post on X.

“Afternoon and evening hours look especially active, and will likely impact travellers,” Niwa posted on X this morning.

“Localised flooding and stronger-type thunderstorms are possible.”

The top half of the South Island, however, was in line for the greatest amount of rainfall – particularly the Tasman and Richmond Ranges – which are both under heavy rain warnings, along with Westland District north of Fox Glacier, Niwa wrote.

By 11.30am, several flights in and out of Nelson Airport had been cancelled, according to the airport’s website.

The heaviest falls were expected to be late afternoon for Golden Bay and into early evening for Richmond/Nelson, Nelson Tasman Civil Defence wrote on Facebook.

“High tide is around 4.20pm, though it will not be as high as last week.”

Parts of Nelson were flooded 10 days ago, and in April emergency services had to rescue two people from floodwaters during another weather event in the region.

Bursts of intense rain are possible for many parts of the North Island, as well as the upper South Island, MetService said.

Northland, Auckland, Great Barrier Island, from 3pm, and Bay of Plenty east of Whakatāne and inland Gisborne/Tairāwhiti, from 8pm, are under heavy rain warnings.

Rain warnings are already in place for Taranaki and inland Whanganui, northern Taihape, southern Taupō and Taumarunui and the Tararua Range. Other parts of the North Island and western South Island are under a rain watch.

A heavy swell warning with waves rising to 6.5m has been made for Kāpiti-Porirua Coast – Ōtaki to Cape Terawhiti from 3am to 3pm tomorrow, with the worst conditions in the morning.

Strong wind warnings have been issued for severe gales in Wairarapa, Wellington and Tararua District from tomorrow morning, while Northland to Taranaki and across to Hawke’s Bay are under wind watches today and tomorrow.

In Auckland, Northland and Aotea Great Barrier Island, a wind watch warns of north to northeast winds possibly reaching gale force, especially in the vicinity of thunderstorms, from 3pm to midnight today.

“The low and associated fronts are expected to bring heavy rain and very strong winds to several areas,” MetService said.

“The rain and strong winds are the result of a rapidly deepening area of low pressure forming off the eastern coast of Australia and crossing the country.”

The rain and strong winds are due to a rapidly deepening area of low pressure forming off the eastern coast of Australia and then crossing New Zealand.

After the low crosses the country, a cold southerly was expected to move up the South Island, making wind and rain not the only thing to watch out for, MetService meteorologist John Law said.

“With cold air rushing in behind this system, it’s going to be a much colder end to the week.”

As the cold air ran across the country, rain will turn to snow across the Canterbury High Country overnight into [tomorrow] morning, impacting the higher roads and mountain passes, MetService said today.

“Temperatures will continue to fall into the weekend, bringing the potential for snow to the Canterbury Plains on Friday.”

The coldest spots will be in Central Otago, where daytime temperatures for Wānaka and Alexandra are only likely to reach 3C or 4C this weekend.

The colder air on Friday also brings the potential of snow to lower areas of Canterbury.

“Cold air and wintry showers will feature in the forecast for parts of the South Island on Friday, but the heaviest snow is expected over the highest parts of Canterbury overnight on Wednesday,” Law said.

“Snow is likely to near sea level on Friday for Canterbury, Otago, Southland and Fiordland. While this snow is likely to be significant and may cause disruptions to travel, at this stage warning amounts are not expected.”

Niwa staff also warned of the possibility of snow, including to lower elevations, from tomorrow.

“A powerful cold front brings a dramatic temperature drop, snow to high elevations, and possibly even lowland snow depending on how a developing low-pressure system tracks,” they posted online.

Road snowfall warnings were issued this morning for the South Island’s Lewis (SH7), Arthur’s (SH73) and Porter’s (SH73) passes from early tomorrow morning, with a few centimetres of snow or flurries expected down to as low as 500m above sea level.

A few centimetres of snow is also possible on the Lindis Pass (SH8) in Central and North Otago, from tonight until the early hours of tomorrow, MetService said this morning.

Squally showers, hail and widespread frost are also on the cards from the weekend, Niwa said.

This week’s forecast is a “dynamic and potentially disruptive weather pattern”, they said.

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