Heavy rain, strong winds, and possible thunderstorms are set to sweep northern and western parts of the South Island on Sunday.
Much of the North Island will see scattered showers with moderate risks of isolated thunderstorms in the west - possibly reaching Auckland in the afternoon.
The Westland Ranges will be hit hardest by the cold front, with up to 110mm of rain, 35mm/h winds, and possible thunderstorms expected.
A heavy rain warning for the ranges is in place until 1am Monday.
Dunedin, Fiordland, Buller, and Nelson should also expect heavy rain with thunderstorms likely, a heavy rain watch is in place.
There's a moderate risk of thunderstorms for Westland and Buller on Sunday morning, spreading to Nelson at midday.
Thunderstorms will bring localised downpours up to 25 mm/h, strong wind gusts, small hail, and even one or two small tornadoes.
From mid-morning, the risk of thunderstorms in Fiordland will increase from low to moderate, accompanied by brief heavy rain and hail.
Nelson is set for a 24C high on Sunday, Invercargill and Queenstown 20C, Dunedin 25C, and Christchurch slightly hotter at a 27C.
Wellington's high is 21C, Taupo 23C, and New Plymouth 22C. Auckland and Napier are hotter at 27C, with Whangarei at 30C.
The wet weather is delivered by a cold front from the Tasman Sea, travelling over the South Island on Sunday morning.
Two Southern Ocean storms tracking close to New Zealand will bring severe gales, snow, and chilly temperatures to the country from Sunday to Wednesday.