Temperature dips in 2012

23:00, Jan 09 2013

The average temperature in New Zealand last year was just 12.5 degrees Celsius, despite December's unusually warm weather, according NIWA's annual climate summary.

That was 0.1C below the 1971-2000 annual average after 2012 started cloudy and wet, and had a particularly cold patch mid-year.

The summary, published today, shows Whakatane won the contest to be the sunniest place in the country, with 2602 sunshine hours, followed by Nelson with 2584 hours, and Tekapo with 2562 hours.

NIWA said cloudy and wet conditions in January and February meant the typical summertime swelter was absent.

The weather analysts said 2012 would be remembered for extremely heavy snowfall on June 6 when afternoon temperatures in Canterbury, Blenheim, around Arthur's Pass, and on the West Coast set new low records for the month, and in some cases broke all-time records.

In the first few days of July, frosts were particularly severe during a period of clear skies and light winds.

Ex-Tropical Cyclone Evan was responsible for extremely high Christmas Day and Boxing Day temperatures between Taranaki and Nelson, but warm windy northwesterly conditions resulted in extreme-maximum temperature records elsewhere during the week around Christmas.

NIWA said annual rainfall totals were less than 80 per cent of normal in the west between Whanganui and the Kapiti Coast, and in Fiordland.

Rainfall was between 80 per cent and 100 per cent of annual normal for the south, west and north of the South Island, and across much of the remainder of the North Island.

In contrast, Gisborne, parts of Central Otago, and between Oamaru and Timaru received more than 120 per cent of annual normal rainfall.

The summary said enhanced easterly winds for the first five months of the year, as well as in August, meant a sunnier than usual year for the west between Te Kuiti and the Kapiti Coast, and for the West Coast of the South Island.

It was the sunniest year on record for Te Kuiti, New Plymouth, Paraparaumu, and Greymouth.

In Contrast, Wairarapa, Wellington, Blenheim, Central Otago and Northland received less than 95 per cent of normal sunshine hours.

Mean annual temperatures were more than 0.5C below average in the northeast of the South Island, and in Wellington, Wairarapa, parts of the Manawatu, and between the Tararua District and Waikato. Elsewhere, mean annual temperatures were generally near or slightly below average.

NIWA said the large-scale climate setting for the year was mainly driven by a moderate La Nina event at the start of the year. In autumn it eased to neutral and had remained there since.

During La Nina periods New Zealand tended to experience more northeasterly winds, which brought more moist, rainy conditions to the northeast parts of the North Island, and reduced rainfall to the south and southwest of the South Island.

The other major climate pattern which influenced this country - the Southern Annular Mode (SAM) - was predominantly positive for much of 2012, although it went negative in the last three months of the year.

SAM was one of the most prominent features of Southern Hemisphere climate on monthly and seasonal time scales. It controlled where and how strongly middle-latitude westerly winds blew, and where the tracks of storms and anticyclones lay across the southern middle latitudes. NIWA said.

In the positive phase of the SAM, storm activity tended to decrease over New Zealand, with more settled weather, while windiness and storm activity increased over the southern oceans.