NZ National Climate Summary - 2004
Forest fires, flooding assessed as the worst in living memory, tornadoes, blizzards, hailstorms and persistent storms with gale force winds characterised a year of dramatic climate extremes. The year produced new records for rainfall, temperatures and sunshine in most months and was dominated by strong stormy westerly and south-westerly winds more frequent than normal.
There were rogue qualities in the overall climate pattern. These included the anticyclones that dominated in January and then gave way to stormy westerlies and south westerlies in February, which produced the most extreme rainfall and flooding experienced in Manawatu and Taranaki since the 1920s.
The year began with very high temperatures accompanied by high winds, producing life-threatening forest fires in early January in Canterbury. These gave way to record rainfall in Taranaki/Wanganui, making flooding the dominant climate hazard by the end of February. June was very warm and July brought another bout of flooding in the Bay of Plenty, while the south stayed extremely dry. August received very persistent cold southerlies, producing blizzards and high winds. Persistent strong, cold, stormy south westerlies dominated the remainder of the year, with December being unusually cold.
2004 was one of the wettest years on record in parts of Bay of Plenty, Manawatu, Kapiti, Upper Hutt and the Wairarapa. Rainfall was more than 125 percent of normal in Manawatu, Wanganui, eastern Bay of Plenty, Horowhenua, and Wairarapa, and at least 110 percent of normal in Waikato, King Country, south Taranaki, Wellington, western Bay of Plenty, Gisborne, Nelson, and Southland. Totals were 75 to 90 percent of average in coastal Marlborough and eastern Otago. Rainfall was near normal elsewhere.
Of the four main centres, Christchurch was the driest with 643 mm (102 percent of average) and Wellington the wettest with 1447 mm (116 percent of average). Auckland received 1331 mm (107 percent) and Dunedin 765 mm (94 percent). Middlemarch, in eastern Otago, was the driest of the sites where NIWA measured rainfall, with only 441 mm (85 percent of average), followed by Alexandra with 492 mm in Central Otago (134 percent of average). Of the regularly reporting rainfall stations, the wettest location in 2004, for which rainfall data are presently available was the Cropp River gauge in Westland, inland in the headwaters of the Hokitika River, with an annual total of 10,920 mm.
The 2004 national average temperature, calculated by NIWA, was 12.3°C, 0.3C below the 1971-2000 normal, and the lowest since 1993. For NZ as a whole, there were seven cooler than average months (February through April, and July through September, and December), four warmer than average months (January, May, June and November), and one month with mean temperatures close to the climatological average (October). The warmest locale was Whangarei, with a mean temperature for the year of 15.3°C (0.3°C below average).
2004 mean temperatures were about 0.3°C below average in most regions, but at least 0.7°C below average in parts of Auckland, King Country, inland Bay of Plenty, coastal Wairarapa, Buller, and inland areas of the South Island.
Sunshine hours were more than 105 percent of normal in coastal Otago, less than 95 percent of normal in Waikato, Taupo, Manawatu, south Taranaki, and the Southern Lakes, and near normal in all other regions. Christchurch was the sunniest of the four main centres with 2096 sunshine hours, followed by Wellington (2073 hours) and Auckland (2066 hours). Dunedin recorded 1746 hours. Nelson was the sunniest centre in 2004, recording 2457 hours, followed by Blenheim with 2393 hours, and then Tauranga with 2360 hours.
Contact for Enquiries
The Ministry of Agriculture and Forestry
Pastoral House
25 The Terrace
PO Box 2526, Wellington
Tel: +64 4 894 0100
Fax: +64 4 894 0720
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