"The temperatures over the weekend and into Anzac Day should be in the late teens to early 20s in the North Island," Coutts said.
"It will be a little bit cooler in the south."
Clear skies, however, mean temperatures will drop in the evenings in most places. And the occasional shower could materialise.
"The nights are getting longer and temperatures will dip to between 10 and 15 degrees in Auckland and Northland.
"In Canterbury and Masterton it will drop to single digits and there could be early morning fog or even frost in the surrounding areas."
On Sunday there will be a few isolated showers northwards of Auckland and about East Cape, otherwise it will be mainly fine. In the South Island, rain will develop in the far south, with a few showers expected in Westland and Buller.
Come Monday showers will develop in the east and in Wellington. It will be mainly fine elsewhere, but again there could be isolated showers from Auckland northwards.
In the South Island, a period of rain will develop in the far southern areas. Elsewhere, there will be a few showers in the west with scattered showers developing in the east, but it will remain dry in Nelson and inland Marlborough.
On Anzac Day it will be mainly fine across the country, with isolated showers in Northland and Gisborne. In the South Island, a few showers are expected in Buller and rain will develop in Westland and Fiordland.
Anzac Day weather at a glance:
Auckland - 20/partly cloudy
Wellington - 16/showers
Tauranga - 21/sunny
Whangarei - 21/partly cloudy
Hamilton - 20/sunny
Christchurch - 16/partly cloudy
Dunedin - 16/partly cloudy