A rescue mission is under way after 30 vehicles became trapped at the top of a Canterbury mountain due to heavy snowfall.

A Fire and Emergency New Zealand (Fenz) spokesperson said one crew from Springfield took a four-wheel-drive up Porters Pass to assist police and roading crews in clearing the road after vehicles became stuck.

“Getting there was the hardest part,” they said.

The New Zealand Transport Agency Waka Kotahi (NZTA) website said State Highway 73 had closed from Springfield to Castle Hill due to heavy snowfall. A further area warning was in place on SH73 from Otira to Castle Hill which read, “Due to snow, no towing and chains essential, drive with care.”

SH7 from Hanmer Springs to Springs Junction remains open with restrictions.

Fenz said only a certain number of vehicles were getting through the snow.

Heavy snow on State Highway 73 at Porters Pass closed the road, trapping a number of trucks and cars about midday.

“We are asking people to stay away from the area and not travel unless absolutely necessary.”

A police spokesperson said there was a report of a crash on West Coast Rd, Springfield involving a car towing a boat about 11.45am.

“A number of other vehicles were reported to be stuck in the area. Contractors were heading up with equipment and it looks like several cars have been released.”

Vehicles had also become stuck outside of Arthur’s Pass heading towards Christchurch and Fenz crews were responding to assist.

Meanwhile, properties in the lower North Island have been inundated by water after heavy overnight rain flooded streets.

Residents in Pahīatua are mopping up this afternoon but fear more is yet to come.

MetService says another burst of rain is due to hit this afternoon.

MetService is also warning thunderstorms, gusty winds and heavy rain will impact much of the North Island, including Auckland.

There is a risk multiple areas will see “localised heavy rain” and winds up to 110km/h.

NZTA also advised that due to strong wind gusts, reduced speed limits were in place on the Auckland Harbour Bridge. Lane reductions may be required and caution was advised, especially for high-sided vehicles and motorcycles.

The wild weather has also disrupted the travel plans of some air passengers this afternoon.

Flooding in Pahīatua after heavy rain hit the Tararua Range and Wairarapa. Photo / Luke Chandler

Flight NZ600 has diverted to Christchurch due to the weather in Wellington. An Air New Zealand spokesperson said the flight will refuel in Christchurch and is rescheduled to depart for Wellington again later this afternoon.

A Pahīatua local said the rain started last night and it was still raining heavily this morning.

She said blocked drains and rising creeks were to blame for the high water levels, and locals were out this morning attempting to remedy the issues.

Heavy rain has caused the town of Pahīatua near Palmerston North to flood.

Photos showed water creeping into homes on residential streets.

According to NZTA’s website, Pahīatua Track was forced to close due to fallen trees and slips.

Residential streets in Pahīatua were flooded due to the heavy rain.

The website reported the road closed at 5.52am and said will be closed “until further notice”.

MetService meteorologist Mmathapelo Makgabutlane said 40 to 60mm of rain has fallen already today, and more is due this afternoon.

“From midday onwards, through to this afternoon and evening, there is another wave of wet weather coming through.”

This is due to a rain band that is sweeping up the country from the east.

Makgabutlane said there are a “number of fronts that are in play and are bringing wild weather to various areas”.

She said a rain band sitting off the east of the country will move over at around midday, bringing thunderstorms, heavy rain and gusty winds to much of the North Island.

For Northland, Auckland, Waikato, the Coromandel Peninsula, western Bay of Plenty (including Rotorua), and general western districts from around Raglan to Kāpiti, as well as the eastern Bay of Plenty, there is a persistent moderate chance of thunderstorms into the early evening.

Additionally, there is a chance a few thunderstorms in the areas of Northland, Auckland, Waikato, the Coromandel Peninsula and the western Bay of Plenty might become severe with dangerous wind gusts exceeding 110 km/h.

Flooding in Pahīatua after heavy rain hit the Tararua Range and Wairarapa. Photo / Luke Chandler

The Tararua Range is under a heavy rain warning which is due to end at 10pm. MetService is reporting 60 to 90mm of rain will fall on top of what has already fallen.

Further south, a heavy rain watch will come into force for Wellington at 1pm today. MetService is warning residents thunderstorms “are possible” and rain amounts may reach “warning criteria”.

While most regions across the country have been battered by rain, wind or snow today, the National Institute of Water and Atmospheric Research (Niwa) reported Whakatu, Hawke’s Bay set a new August temperature record, reaching 24.6C. Records for the area date back to the 1930s.

Niwa said less than 600km to the south, Cass in Canterbury had only managed to reach 2.5C today.

Rachel Maher is an Auckland-based reporter who covers breaking news. She has worked for the Herald since 2022.