Keep winter woollies handy - summer could be cool

Don't pack away your winter clothes just yet - the early signs are that we may be in for a colder summer than usual.

The sea temperature at Auckland University's Leigh marine laboratory has been colder than usual since February and is still only 15.8C, almost 2C colder than normal for this time of year.

"My guess is that it will be a colder than average summer," said the laboratory's climate monitoring supervisor, Jo Evans.

But as usual, just as summer starts, forecasters are hedging their bets. Dr Jim Salinger of the National Institute of Water and Atmospheric Research, said he saw no reason to change Niwa's last long-range forecast for "average or near-average" temperatures in the North Island between November and January.

Niwa figures show an average nationwide air temperature in November of 14.3C, or 0.6C above average.

But the above-average temperatures were in the southern North Island and South Island. Auckland Airport recorded the highest November sunshine hours since records started there in 1963, but with temperatures slightly below average and only half the usual rainfall.

As a small country in the middle of the ocean, New Zealand's climate is dominated by what happens at sea.

Niwa's sea surface temperature measurements, taken from satellites, showed colder than usual seas around most of the country in October, and its official outlook predicted that the sea would stay about 0.5C colder than usual from November to January.

But in November, the colder-than-average area shrank to a small patch off Northland's east coast and a larger area around the southern South Island.

The experts agree that the weather is displaying "mild El Nino" conditions, when the trade winds across the Pacific weaken, bringing less warm surface water to the seas around New Zealand and Australia and more relatively cold, dry weather.

But the former Leigh laboratory director who set up Leigh's daily monitoring system in 1967, Dr Bill Ballantine, said this year's patterns were "peculiar even by peculiar standards", starting with the storm that produced February's widespread floods.

"Since then we have had a return to nearly normal and gone down again several times. A fortnight ago it went down sharply again ... we basically don't understand it at all."