New Zealand National Climate Summary - The Year 20

New Zealand National Climate Summary - The Year 2006

2006:

Severe Winter Snowstorms; Floods, Wind Storms, Destructive Tornadoes; Variable Temperatures, Yet Sunny Overall

Erratic and sometimes extreme, New Zealand’s climate for 2006 will probably be most remembered for one of the severest winter snowstorms in decades, a very windy spring, and a cold start to summer late in the year. So it may surprise people to hear that 2006 was also very sunny in the southeast of the South Island, and generally sunny in many other regions.

“The year was marked by too little rain in some places and too much in others”, says NIWA Principal scientist Dr Jim Salinger. Extreme climatic events continued, with severe snowstorms, floods, destructive tornadoes, and windstorms. Excessive winter rainfall produced severe flooding in the Wairarapa, but it was very dry for the year in Otago. Of the main centres, Dunedin was dry and sunny, while Wellington and Christchurch were very wet.

“The year saw a swing from a La Niña to an El Niño climate pattern. The first quarter of the year was dominated by weak La Niña-like characteristics in the equatorial Pacific, and frequent troughs of low pressure often over New Zealand. From September onwards weak–moderate El Niño conditions in the tropical Pacific had developed, with a noticeable increase in windiness, and more frequent south westerlies than normal over the country.”

“There were numerous heavy rainfall events during 2006, about 18 of which produced floods. Notable snowfall events occurred on nine occasions, mainly in high country areas from mid-autumn to late winter, with ski areas having an extended season. Other climate extremes included a summer heat-wave, four tornado incidents, three severe hailstorms, and many damaging windstorms”, said Dr Salinger.

The national average temperature in 2006 was 12.4 °C, 0.2 °C below the 1971 – 2000 normal. Thus, 2006 ended up very close to the 1971-2000 normal, as a consequence of very warm months (April, September) offsetting some very cold months (March, June, December).

Sunshine hours were more than 110 percent of normal in Bay of Plenty, Southland, coastal Otago, and inland South Canterbury, with Invercargill recording its sunniest year on record. Totals were at least 105 percent of normal in many South Island regions, as well as Northland, Auckland, and Gisborne. Sunshine hours were near normal elsewhere. Nelson was the sunniest centre in 2006, recording 2580 hours, followed by Blenheim with 2528 hours, and then Tauranga with 2507 hours.

2006 was much drier than average (with totals less than 75 percent of normal) throughout parts of Central Otago and the Awatere Valley in Marlborough; Clyde in Central Otago recording its driest year in more than 20 years, with only 286 mm for the year. Rainfall was also below average (75 to 90 percent of normal) in parts of Northland, Coromandel, North Taranaki, Buller, Nelson, Marlborough, north and east Otago, and South Westland. However, rainfall was well above average (at least 125 percent of normal) in parts of Wairarapa, Wanganui, Wellington, and Canterbury, and at least 110 percent of normal in Taupo, Manawatu, Kapiti, North Westland, and coastal areas of Southland. Wellington recorded its wettest year since the late 1970s. Rainfall was near normal elsewhere.

Records for the year

NIWA analyses of month-by-month records and preliminary end of year data show:

• The highest annual mean temperature recorded for the year was 15.8 °C recorded at Kaitaia.

• The highest recorded extreme temperature of the year occurred during a heat-wave in Central Otago toward the end of January. Alexandra recorded maximum temperatures of 36 °C for three consecutive days from the 27-29th (unheard of in their historical record, commencing in 1930).

• The lowest air temperature for the year was -14.0 °C recorded at both Tara Hills, Omarama on 14 June and Fairlie on 28 June. The minimum air temperatures were –10 °C or lower in parts in inland South Canterbury and/or North Otago, on nine days between 14 and 29 June.

• April was the warmest since 1978.

• June was the equal coldest (with 1992) since 1972. • September was the 3rd warmest on record.

• December was one of the coldest since 1945, approximately equal with Decembers 1946 and 2004.

• The highest recorded wind gust for the year was 180 km/h was recorded from the northwest, at Southwest Cape (Stewart Island) on 2 September, a new record for a wind gust at that site. Mean wind speeds reached 128 km/h.

• The driest rainfall recording locations were Alexandra in central Otago with 266 mm of rain for the year, followed by Clyde with 286 mm.

• Of the regularly reporting gauges, the Cropp River gauge in Westland, inland in the headwaters of the Hokitika River, recorded the highest rainfall with a 2006 annual total of 11370 mm.

• Dunedin was easily the driest of the five main centres with 641 mm and Wellington the wettest with 1579 mm. Hamilton received 1155 mm, Auckland 1263 mm, and Christchurch 884 mm.

• Nelson was the sunniest centre in 2006, recording 2580 hours, followed by Blenheim with 2528 hours, and Tauranga with 2507 hours. Auckland was the sunniest of the five main centres with 2189 sunshine hours, followed closely by Christchurch (2169 hours), and Wellington (2159 hours). Dunedin recorded 1960 hours, and Hamilton 1996 hours. –

ENDS

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