Beach and barbecue weather in much of the North Island but icy conditions at the bottom of the South Island are on the cards for Waitangi Day.
The northeast is the pick of the bunch, with Napier reaching a country-wide high of 28C and Gisborne a close second on 27C.
Waitangi and much of Northland will also be top spots, with fine weather and a high of 26C forecast - perfect for Prime Minister Jacinda Ardern's Waitangi Day breakfast barbecue.
Meanwhile Invercargill is being battered by a brisk southerly, restricting the high to 14C. Showers are forecast for much of the day.
Metservice meteorologist Claire Flynn says the eastern parts of the North Island will be mostly fine for the day, while the western areas will have a bit of cloud and the odd shower becoming less frequent over the day.
Auckland will reach a high of 24C, and the odd morning shower will clear for a mostly fine afternoon.
A southerly change is expected to come through Wellington about midday, bringing the odd shower, before making its way up the east coast.
"It has been quite warm up the East Coast already today, but that southerly change will cool things down in the late afternoon," Flynn says.
"It will work its way up from Wellington during the afternoon, through Wairarapa, Hawke's Bay and Gisborne bringing with it cloud and drizzle."
The southerly system has already brought cooler temperatures to much of the South Island, where Christchurch and Queenstown are forecast to reach highs of 17C, and Dunedin 16C.
There will be a few showers throughout much of the South Island in the morning, but by midday there should just be the odd shower in the ranges and in the far south.
Canterbury and Marlborough will be covered in cloud for most of the day.
Nelson will be the pick of the South Island main centres, reaching a high of 24C and fine weather forecast all day.
Auckland: Fine spells increasing, but one or two morning showers. Southwesterlies dying out at night. High of 24C.
Tauranga: Mostly sunny. Gusty westerlies, easing evening. High of 26C.
Hamilton: Fine spells increasing, but chance morning shower. Southwest dying out evening. High of 24C.
Napier: Mainly fine with westerlies. Winds changing southerly late afternoon then drizzle developing from early evening. High of 28C.
New Plymouth: A few showers clearing to fine in the morning. Westerlies turning southeast at night. High of 22C.
Wellington: Fine at first. Cloud increasing and a brief shower about midday with a southerly change. High of 22C.
Nelson: Fine. Southwesterlies. 24C.
Christchurch: A few morning showers clearing but remaining mostly cloudy. Southwesterlies dying out. High of 17C.
Queenstown: Few early showers, then becoming fine. Southwest dying out. High of 17C.
Dunedin: Cloudy periods, morning showers clearing. Strong southwest easing. High of 16C.