The chill should ease by Monday evening. Photo: 123RF

MetService says there will be a noticeable dip in temperatures overnight.

A cold front was moving up the South Island on Sunday, which will cross the North Island on Monday, bringing with it strong southwesterly winds.

Meteorologist Alwyn Bakker said it follows a few days of warmer than usual temperatures.

"As this cold front comes through, it will be clearing out a lot of that warm, humid air - so temperatures will be dropping, especially overnight."

Bakker said in some ways, it will be a return to the temperatures expected at this time of year.

With a strong cold front moving north across NZ tonight, much chillier temperatures will be widespread on Monday.While mid-to-upper teens are still expected in the North Island, the lower South Island will struggle to get out of the single numbers on Monday afternoon.

On Sunday afternoon, MetService had road snow warnings in place for Milford Road, Fiordland and the Crown Range, and strong wind watches from Dunedin to Stewart Island.

"There is a moderate risk of thunderstorms for the far south of Fiordland and for Stewart Island from late afternoon," MetService said on its site.

Heavy swell warnings were in place for Wellington, Wairarapa and the Kapiti-Porirua Coast, and there were strong wind watches for Dunedin, Coastal Southland, Stewart Island / Rakiura and Clutha.

The chill should ease by Monday evening, MetService said.