Weather: 'Numerous' vehicles stranded, flooding in Pahiatua

It's set to be a wet Sunday for many New Zealanders as an "active weather system" moves across the country.

A number of severe weather watches and warnings were in place with strong winds and heavy snow also expected for parts of Aotearoa.

But temperature-wise, it's "a tale of two islands" with significant differences forecast between the North and South.

Motorists in Canterbury are being urged to consider delaying travel this afternoon thanks to the poor conditions.

SH73 is closed from Springfield to Castle Hill, and police said "numerous" vehicles were stuck at Castle Hill and the Lake Lyndon area.

"Anyone who has to travel is urged to ensure they are doing so with the appropriate equipment, such as snow chains.

"We also strongly suggest checking Waka Kotahi’s journey planner before embarking on travel to ensure the roads you intend to travel are still open.

"If you are out on the roads please keep your headlights on, slow down, make sure you are observing a cautious following distance, and put any distractions away."

Flooding hit "several dozen" properties in the northern Wairarapa town of Pahiatua overnight and caused water damage to a few, the Tararua District Council said.

However, the water receded on Sunday, with the council's roading contractor, Downer NZ, clearing roads and pumping water from the streets.

The wild weather means Pahiatua Track remains closed due to slips, and some roads remain closed.

Other roads have been reopened, but drivers are urged to remain cautious - and everyone is reminded of the dangers of flood water.

"Always assume that flood water is contaminated. Contaminated flood water can make you sick. Make sure you wash your hands, clothes and property after contact with flood waters," Tararua District Council said on Facebook.

"Never try to walk, swim or drive through flood water. Besides being unsafe, driving through flooded streets causes waves and impacts properties.

"River levels are very high. Please stay away from low-lying areas and be careful."

MetService has issued an orange heavy rain warning for the Tararua Range until 10pm tonight.

"Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible," the service warned.

"Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously."

It's because of an "active trough of low pressure" moving east across the country, MetService explained, adding it could bring strong winds to parts of the North Island and the northern South Island.

"With an active weather system moving across New Zealand today and tomorrow, it might pay to keep an eye on the latest rain radar."

And a heavy rain watch is in place for Wellington until 9pm tonight.

The capital was warned that thunderstorms are possible.

A strong wind watch is in place for Gisborne, Hawke's Bay, Taihape and Wairarapa north of Masterton until 5pm today.

"Northwest winds may approach severe gale in exposed places," MetService warned.

"Moderate chance of upgrading to a Warning."

The North and South Islands are set for very different average temperatures today.

"Sunday showdown: a tale of two islands," NIWA Weather said on X.

"Spring Island vs. Winter Island—two places, two seasons, one epic contrast! Which side are you on?"

An accompanying graphic showed the North Island would be much balmier than the South today.

"Heavy snow is possible for inland parts of northern Canterbury and Marlborough on Sunday, and then the southern South Island on Monday," MetService said.

Heavy snow watches are in place for inland parts of Canterbury north of Springfield and Marlborough south of SH63 until 10pm tonight and central Otago south of Lake Wakatipu and Roxburgh, Clutha, Southland, Stewart Island and Fiordland south of George Sound until 5pm tomorrow.

And number of road snowfall warnings are in place around the country.

"People are advised to keep up to date in case further areas are added or upgraded," MetService said.