Santa will roll out sunny skies

Warm temperatures are predicted for Christmas Day, meaning even Santa can cool off. Photo / APN

Much of NZ can expect a dry Christmas Day, but expect the weather to cool in the next few days

Santa is expected to gift sunny skies to much of New Zealand on Christmas Day but wise men will keep a brolly close at hand.

Summer officially starts today and WeatherWatch head analyst Philip Duncan said the warm weather of the past week was likely to cool in the next few days.

For most Kiwis, the first week of summer would be cooler than the last week of spring.

Long-range patterns suggested high-pressure systems would continue to thwart "rainmakers" from the Southern Ocean pounding the country, Duncan said.

For that reason, the days around December 25 would more likely be dry than rainy.

"I'd say the chances are stacked against the rainmakers rather than for them, but you never know."

History also showed settled and dry Christmas Days were the norm for Auckland, Hamilton, Tauranga and Christchurch.

Heavy rain, thunderstorms and severe gales battered central parts of the country this week but Duncan said these conditions would become more rare as the festive season approached.

The National Institute of Water and Atmospheric Research (Niwa) seasonal climate outlook suggested hotter-than-normal or average temperatures were likely for most regions this summer.

An unusually hot summer was least likely for the west of the North Island and east of the South Island.

Niwa will have specific Christmas Day predictions in a fortnight.

Controversial "Moon Man" Ken Ring has predicted cloudy, scattered showers for Auckland in his annual "almanac", and reaffirmed these predictions this week.

Ring predicts two heat waves this summer - one in mid-January and the other across most of February. "The best time for holidays is probably December 8-20, and January 6-19."

Ring expected New Zealand to avoid a repeat of last summer's drought, which Niwa said was the worst in 67 years.

Columbia University's International Research Institute for Climate and Society said there were "nearly even odds" for El Nino conditions to develop next year, which could make 2014 the hottest ever. The waters north of New Zealand were expected to warm next year, possibly driving up global temperatures.