Thursday night would be particularly cold in Queenstown, with temperatures dipping to 1C.
Dunedin and Queenstown would bear the brunt of the cold weather, with highs of 12C on Thursday.
“We’re going for a maximum of 11C in Queenstown on Thursday and a maximum of 14-15C for Christchurch,” Gullery said.
Two road snowfall warnings were now in place for southern roads.
Snow showers were expected on the higher parts of Milford Rd and Crown Range Rd on Wednesday night and Thursday morning, with snow accumulating above 800 metres.
For the North Island, Gullery said the cold southerly will be heading to southern regions on Thursday night, moving further north on Friday, and bringing rain.
Katie Oliver is a Christchurch-based Multimedia Journalist and breaking news reporter.
Sign up to The Daily H, a free newsletter curated by our editors and delivered straight to your inbox every weekday.