"It's like we're heading towards summer, rather than getting out of it," he said.
Auckland would likely have warm weather until the third week of May.
In the South Island temperatures would be between 18C to 24C, well above average.
"It's not normal weather.
"There's a mixture of hot and warmer to cooler days in the South Island."
Forecast
Whangarei
Today: Fine spells. Light winds. 24C.
Tomorrow: Mostly sunny, with light winds. 24C.
Auckland
Today: Fine spells, chance evening showers. Northerly breezes. 22C.
Tomorrow: Mostly sunny, chance shower after midday. Northwest breeze. 22C.
Tauranga
Today: Cloudy periods, few showers clear evening. Light winds. 21C.
Tomorrow: Morning cloud, then mostly sunny. Chance shower. Light winds. 22C.
Wellington
Today: Cloudy periods. Northwest strengthens, gust 90 km/h. 19C.
Tomorrow: Tomorrow: Occasional rain. Strong northwest gusting 90 km/h, easing. 19C.
Christchurch
Today: High cloud thickening. Gusty northerlies. 24C.
Tomorrow: A sunny day. Northeasterlies developing. 19C.
Dunedin
Today: High cloud. Brief afternoon rain. Gusty northerlies. 21C.
Tomorrow: A sunny day. Northeasterlies developing. 19C.