While temperatures have been gradually cooling as summer turns into autumn, expect that transition to speed up as the weekend approaches.
A high currently over the country is expected to head offshore, making way for a low, bringing with it rain and wind, including some from the south.
"The polar jet is set to return in a big way this coming weekend," the National Institute of Water and Atmospheric Research (NIWA) said in a post on social media, saying an "Antarctic air mass" was "likely bound for New Zealand".
The polar jet is set to return in a big way this coming weekend
— NIWA Weather (@NiwaWeather) March 11, 2024
Follow the as it tracks an Antarctic air mass likely bound for New Zealand!
The cold spell may come with elevation snow in the South Island & May-like temperatures that linger into next week... pic.twitter.com/fsQ2p5VQ8r
It will make itself felt on Thursday, MetService forecast, at first particularly in the southern parts of the South Island.
On Friday the rain will come, over western parts of the North Island and in a band across the South Island, between Hokitika and Canterbury.
By Saturday, it will be wet and windy across much of the North Island and the eastern coast of the South.
A strong wind watch was already in place for Fiordland and Southland on Tuesday night, with northwesterly winds possibly approaching gale-force in exposed places, according to MetService.
Before it all turns bad however, Wednesday should see early showers in the North Island making way for the sun in the afternoon. The hottest place will be Hawke's Bay at 27C, and the coldest Wellington, peaking at 20C.
As for the South Island, early cloud across the north and east should clear by the afternoon, but prove sticker on the West Coast. Peak temperatures range from 14C in Invercargill to 22C in Nelson.
NIWA said the incoming chill would make March feel more like May, and linger into the following week. It could get as low as 7C in Hamilton overnight at the weekend, MetService's forecast showed - chillier than Invercargill's expected 7C.
"Even in a place like Auckland, you might be struggling to get to 20C on Saturday," forecaster Ben Noll told NZME.
He said this month could be only the second month since 2017 to record a below-average temperature, though autumn as a whole was still expected to show a warming trend.