KEY POINTS:
It was a December to remember for its southerly bite and bitter temperatures to match.
The country's climate summary for last month confirmed what everyone already knew: Temperatures were well below average, with some areas having their coldest December in 60 years.
The data, released yesterday by the National Institute of Water and Atmospheric Research, showed the national average temperature was 13.7C - 1.9C below normal and 3.8C below the average in December 2005, which was the third warmest December on record.
Niwa principal climate scientist Jim Salinger said frequent cold southerlies were the culprits. "It was certainly more like the end of October than early summer," Dr Salinger said.
"We had more low pressure systems to the east of the North Island, and more highs in the south Tasman Sea, and between them they produced a current of southerly air over New Zealand."
But he said the pattern was changing and a return to normal summer temperatures could be expected soon.
Many places around the country, from Kaitaia to Kaikoura and Arthurs Pass, had their coldest Decembers on record as mean temperatures reached up to 3C below normal. Arthurs Pass had an average of just 8.1C.
The average temperature in Auckland was 16C, 2.1C lower than usual, and 12.7C in Wellington, the coldest December in more than 70 years despite the capital being the sunniest of the main centres.
The north of both of the main islands had more sun and about half as much rain as normal. While Auckland and Hamilton enjoyed drier-than-average climes, Christchurch was 2 times wetter than normal. Parts of Canterbury and Otago also had above-average rainfall and Middlemarch had its wettest December on record.
Extremes included a wind gust of 148km/h recorded at South West Cape and a hailstorm in Riwaka on December 1 that damaged apple orchards in the area.
Dr Salinger said the chilly month was not a counter-argument to global warming, as global temperature trends continued to surge.
"You can have months where weather patterns just get stuck and this is what happened here."
Nor did it signal the start of a general deterioration in weather conditions. "Patterns can jump around, so you don't get too perturbed when you have a month of southerlies. In 2005, we had a month of northeasterlies in December and the result was [an average temperature of 17.5C]."
Chilly times
* Average temperature nationally was 13.7C, 1.9C below average.
* The highest temperature was 31.5C at Blenheim Airport, the lowest was -2.5C at Chateau Tongariro. Pukekohe (4.4C), Christchurch airport (0.1C) and Manapouri, West Arm (-0.6) all had record low temperatures.
* New Plymouth, Wanganui and Blenheim had their coldest Decembers in at least 60 years.
* Of the five main centres, Auckland was the warmest and driest, Christchurch the wettest and Wellington the sunniest
* Sunshine hours were higher than normal in the north of the North and South islands, and less than normal in Manawatu and the Kaikoura coast.
