Weather: Overnight temperatures to plummet in chilly change for NZ

Forecasters say several centimetres of snow is possible areas above 800m in the South Island and Otago's Crown Range Rd may get covered. Photo / George Heard

Forecasters are anticipating a noticeably chilly change to the sticky humidity that’s been hanging about New Zealand, with a cold front bringing snow to the south today and single-digit overnight lows for the North Island tomorrow.

The “strong” south-westerly change has prompted MetService to issue road snowfall warnings and strong wind watches across the South Island this afternoon – with heavy swells also on the cards for coming days.

Snow showers were expected in higher parts of Otago’s Crown Range Rd and Fiordland’s Milford Rd overnight, with several centimetres of snow possible in areas above 800m.

In Dunedin, southwest winds could reach severe gale strength in exposed places overnight – with a strong wind watch also in place for coastal Southland, Stewart Island and Clutha from mid-afternoon.

MetService meteorologist Alwyn Bakker said the wintery weather was being caused by a cold front moving across the lower South Island late on Sunday.

🟠❄🚗 Road Snow Warnings Issued 🚗❄🟠

We've just issued Road Snow Warnings for the Crown Range Road and the Milford Road, both overnight tonight.

Crown Range: Expect 1 - 3cm of snow to settle above 800m.

Milford Road: Expect 1 - 2cm of snow to settle above 800m. pic.twitter.com/9vEX4YdwqP

— MetService (@MetService) April 22, 2023

“With that cold front, there’s a lot of cold air following it – which is what’s triggering those two road snowfall warnings.”

Motorists driving those routes should be mindful of the weather conditions, he said, and ensure they had snow chains.

“If you’re not confident driving in it, then don’t until it’s calmed down.”

The front was forecast to further move up the country tomorrow, bringing cooler temperatures to the North Island early next week.

There's some low cloud about today 🌫

In this gif from Milford Sound Airport, you can see cloud clinging to the tops, and even sneaking lower at the end of the clip. pic.twitter.com/aXqJ2JCFEr

— MetService (@MetService) April 22, 2023

Overnight temperatures were forecast to plunge to 8C in Auckland and Wellington, 7C in Tauranga – and to just 2C in Hamilton and 1C in Taupo – on Monday night.

“It will be cold in comparison to what we’ve had previously, with overnight temperatures getting into those single digits,” Bakker said.

“While temperatures in parts of the upper North Island will hang about in the double digits for a while longer, inland places will get cooler temperatures overnight.

“It’s been quite muggy, so some people will find this a nice relief, but others might not be so keen.”

🌊🌊 Heavy southwesterly swells (brought about by the southwesterly change) are expected to bring large waves to South Island coasts on Sunday, reaching the North Island on Mondayhttps://t.co/y7sa5Ofj1O pic.twitter.com/HwcT8eykw6

— MetService (@MetService) April 22, 2023

The same low-pressure system was also forecast to bring heavy swells and large waves to South Island coasts today – and around the North Island tomorrow.

Following the cold front, a ridge was expected to bring better weather conditions around New Zealand.

On Anzac Day, MetService was forecasting partly-cloudy weather in the west of the North Island, with isolated showers developing north of Kapiti, and cloud in the east clearing to fine conditions.

The South Island could expect mainly fine weather in the east on Tuesday, apart from showers developing in the south and others spreading north of Fiordland.