NIWA Media Release15 December 2011 Season's Greetings from La Niña?

What can we expect weather-wise this holiday period? NIWA’s principal scientist climate Dr James Renwick says, “It’s too early to say for sure how Christmas itself will be, but if the La Niña influence continues, New Zealand should be in for a mild and relatively settled few months over the summer”.

“Since 1 December, La Niña has been bringing its typical mix – warmer than normal in many parts of the country, wet in places exposed to the north, such as parts of Northland, Auckland, Taranaki and Nelson, and dry in many other places, especially the south and west of the South Island.”

NIWA’s climate outlook for summer, calls for near- or above-average temperatures in most places, a chance of drier than normal conditions in many parts of the country, and a bit less wind than normal.

As is also typical of a La Niña summer, the northern half of the North Island is likely to be a little wetter, with normal or above normal rainfalls likely.

Looking back, what has the weather been like over the years on Christmas Day?
Dr Renwick looked at the historical records in the National Climate Database, to assess the best and worst of Christmas days past.

“It’s clear that Christmas can deliver just about any kind of weather,” he said.
Sometimes, Christmas Day can be beautifully fine across the country, such as in 2009 when most of New Zealand basked under a big anticyclone, and Dunedin hit 28 degrees.

Christmas of 1988 was similarly balmy almost everywhere, with sunny skies and little wind.
“On the other side of the ledger, wet and wintry conditions can arrive in time for the roast turkey and steamed pudding. In 2007, many main centres were wet on three consecutive days: Christmas Eve, Christmas Day, and Boxing Day.”

In 1987 over 20mm of rain fell in many of the main centres on Christmas Day.
“Christmas 1975 was a cracker – a very large storm off the east coast of the South Island delivered cold southerlies and rain to many parts of the country.”

Rain fell in all the main populations centres around the country, and the thermometer made it only to 12 degrees in Dunedin, and 14 degrees in Christchurch.

“Cruelly, it had been 28 degrees in Christchurch only the day before,” said Dr Renwick.

Whether or not a winter’s day is a problem for Christmas depends a bit on whether the focus is tucking in to a hot dinner, or having a day at the beach.