Auckland and the upper North Island are in for above-average temperatures in the coming months, following a December that was warmer and sunnier than usual.
Warmer than normal sea temperatures are also expected until the end of March, according to Niwa's three-month climate outlook, released today, but the best picks for hot swimming spots will be along the east coast.
The outlook shows sea surface temperatures have been warmer than normal for the past year. Last month, the sea surface temperature was 0.9°C above the normal December temperature.
The increase was the largest monthly deviation from the normal temperature for the year, and marked the 12th consecutive month that the country's sea surface temperature had been warmer than usual.
According to the Niwa summary, those who want to make the most of the warmer seas should head east, with above average sea surface temperatures reintensifying in the area between the North Island and Fiji.
However, warmer than normal sea surface temperatures for the whole country were expected until the end of March.
Above average air temperatures were also on the way to the top half of the country, while those in the South Island should get above average or normal temperatures until the end of March.
Niwa expected rainfall levels for the top part of the North Island to be above normal or normal for the three months. Most other parts of the country should expect near normal rainfall levels until the end of March, with normal or below normal levels in the Nelson-Marlborough region.
Meanwhile, Auckland was hotter and sunnier than usual last month - but it was also wetter, with 130 per cent of the normal rainfall for December.
Auckland recorded a mean temperature of 19°C, 0.8°C above average, as well as 222 hours of sunshine, 112 per cent of the norm. But it was also wetter than normal for December, with 113mm of rainfall, 30 per cent above the norm.
Of the six main centres, Wellington was driest and sunniest, Auckland was warmest, Dunedin was the coolest and cloudiest, and Tauranga was wettest.
Niwa said most of New Zealand was hotter than average last month, with a nationwide average of 16.6°C.
Rainfall was below normal or well below normal for parts of Taranaki, the Central Plateau and the lower North Island, as well as northern Marlborough, the Mackenzie Country and parts of Central Otago. Rainfall was above normal in northeastern parts of the North Island, including areas of Northland, Coromandel Peninsula and Bay of Plenty.