Metservice meteorologist Andy Best said warm north-westerly winds were driving unusually high temperatures in the South Island.
Kaikoura has a maximum temperature of 22C and Christchurch 23C today. That was 6C above average for this time of year.
Gore and Invercargill would reach 19C, also about 6C above average. It will be a balmy night for the South Island, with temperatures 6C to 8C above average.
Most of the North Island will remain fine tomorrow, with Hastings expected to reach 25C (5C above average) and Napier and Gisborne 24C.
In the South Island, Kaikoura would reach 27C - around 12C higher than average for this time of year. Asburton and Alexandra would reach 24C, Christchurch and Blenheim 25C.
It will cool down tomorrow evening. But on Monday, warm conditions will continue, especially between Masterton and Hamilton in the North Island. Hastings and Gisborne would be in the mid-20s. The South Island would also remain warm.
There is currently a strong wind watch in place for Canterbury, which lasts until tomorrow morning. The rest of the South Island east of the Southern Alps also has a strong wind warning in place, with winds possibly reaching 130km/h tonight.
There is also heavy rain warning in place for the bottom half of the South Island, which lasts until tomorrow afternoon.
