With air temperatures well below freezing, participants in the annual L Street Brownies' Polar Plunge take a swim in the ocean in Boston, Massachusetts January 1, 2014. REUTERS/Brian Snyder
With air temperatures well below freezing, participants in the annual L Street Brownies' Polar Plunge take a swim in the ocean in Boston, Massachusetts January 1, 2014. REUTERS/Brian Snyder

The year 2013 has been recorded as New Zealand's second hottest year, according to Auckland University climate scientist Dr Jim Salinger on Monday.

Based on data compiled from 22 land stations and three islands, Dr Salinger said 2013's annual mean temperature was nearly one degree higher than average. New Zealand's average temperature was recorded at 0.84°C above the long-term average, just a few knots away from the 1998 peak of 0.89°C above average.

With air temperatures well below freezing, participants in the annual L Street Brownies' Polar Plunge take a swim in the ocean in Boston, Massachusetts January 1, 2014. REUTERS/Brian Snyder

March, July, Aug and Nov were the months that gave off the mean temperatures that went above average. These mean temperatures were recorded in Masterton, Omarama, Timaru, Invercargill and the Chatham Islands.

Moreover, New Zealand's winter season of 2013 was found to be the warmest, with temperatures hitting 1.3 degrees above the long-term average. Dr Salinger said that in the past decade, only the years 2004 and 2009 had cooler than average years.

Preliminary data released by the World Meteorological Organisation (WMO) for the Jan-Nov 2013 period showed the global mean temperature hit 0.49°C above the long-term (1961-1990) average of 14°C.

"New Zealand regional temperatures have warmed by 0.5°C since 1950 and over 1°C overall," Dr Salinger said.

"This is similar to what has occurred globally, and the general trend is expected to continue."

He noted 2013 came off the sixth-warmest year since global records started almost 150 years ago.

Since 1985, no year has recorded a below-average global mean temperature. In fact, ten of the world's warmest years occurred in the past 12 years, 2002-2013.

Dr Salinger said the prevailing Interdecadal Pacific Oscillation (IPO) is negative, which meant more easterlies and north easterlies with above average temperatures.

"At the same time sea surface temperatures were above average by around one degree Celcius, especially surrounding the South Island and to the east," he said.

Dr Salinger advised Kiwis to brace for more erratic weather conditions since El Nino-Southern Oscillation (ENSO) neutral conditions are expected to continue until winter 2014. Negative IPO conditions meantime will last for the remainder of 2014.

"These conditions are presaged to bring above average temperatures of 0.2 to 0.6°C above average for the New Zealand region," he said.