Weather: Antarctic blast may brush South Island next week; heavy rain, strong winds predicted over weekend

Forecasters are predicting a “polar blast” is possible for parts of the South Island early next week, accompanied by snow at low levels.

It comes as the top of both islands are expected to be struck by heavy rain and strong winds at the weekend, with moderate confidence severe weather warnings will be issued for several areas.

Metservice meteorologist Leigh Matheson told the Herald the lower South Island may experience a “glancing blow” with the Antarctic blast seeing single-figure temperatures to kick off the new week.

Matheson added snow is possible to low levels for Invercargill, Dunedin and potentially Christchurch.

“It doesn’t look like [there will be] a lot of precipitation. It doesn’t look like a big snow event, just really cold,” Matheson said.

She said at this stage, weather models were forecasting a southerly outbreak on Monday, issuing a “glancing blow” for the lower South Island before it moves on to the Chatham Islands.

“There will be southerly gales pushing up into the North Island as well, but not as cold as what the lower South Island is getting. There’ll be a reasonably cold southerly coming into Wellington.”

She added it was something for the lower South Island to “keep an eye on”.

“It’s just going to remind people that although it seems like we’re getting close to spring, winter is very much still around. A typical winter’s day in the far south.”

Auckland was predicted to have a cool Monday, but “nothing outrageous”.

➡️ A significant weather pattern change is expected in late August, September...

A robust jet stream is forecast to extend from the Indian Ocean to New Zealand, leading to more unsettled conditions & spells of unseasonable warmth & wind, potentially lasting for several weeks 🌬️ pic.twitter.com/YWrrcmvzgJ

— NIWA Weather (@NiwaWeather) August 13, 2024

Meanwhile, MetService is forecasting a weak front to come onto the South Island late on Thursday, bringing an extended period of rain to the West Coast. It would die over the South Island on Friday.

“Saturday is a little more interesting,” Matheson said.

A broad low coming from the Tasman Sea is set to bring a period of rain to most northern parts of the North Island and the upper South Island.

Matheson said it was going to move through “fairly quickly”.

“For places like Auckland, it’s sort of a period of rain on Saturday which eases a bit and then another period of rain on Sunday.”