Climate Summary: February 2004
According to the National Institute of Water and Atmosphere (NIWA), February was characterised by:
- Rainfall: Extremely wet, with devastating floods in the centre, south and west of the North Island;
- Wind: Much windier than usual, especially over the North Island;
- Temperatures: Below average overall, especially in the South Island;
- Soil moisture: Significant deficits persist in central Marlborough, Canterbury, and Otago, but surpluses in some North Island areas; and
- Sunshine: Extremely low in the south and west of the North Island.
Thirty monthly historical rainfall records were swept aside in a number of NZ regions during February. Rainfall was very much above average in the south and west of the North Island from Waikato to Wellington, including Wairarapa. It was a month of climate extremes, with seven heavy rainfall and at least three damaging high wind events. The reason for the exceptional climate pattern was an unusually high number of depressions ("lows") to the south of the South Island, which often intensified as they passed over NZ. There were very few of the typical late summer anticyclones ("highs"). This pattern produced the strongest westerlies in over 60 years of records for February over the North Island, and south-westerlies over the South Island.
More than 1000 mm of rain was recorded in the Tararua Ranges for the month. This was due to a number of high rainfall-flood producing events, on 1 February, and especially between the 14th and 18th. The latter produced the most disastrous floods in the Wanganui and Manawatu/Rangitikei region for many decades, as well as flooding in southern Hawkes' Bay, Wairarapa, Lower Hutt, and Picton. Hundreds of people were left homeless, considerable areas of farmland were inundated by silt and floodwaters, many rivers breached their banks, sheep and cattle were drowned or were swept away by floodwaters, many bridges were damaged, and numerous roads closed, along with power, gas and water supply outages to tens of thousands of people.
Further flood-producing rainfall occurred in parts of Northland, Auckland, Coromandel, Waikato, Bay of Plenty, King Country, and Taranaki on the 28th. Rainfall was also above average in most other regions of NZ. Many locations experienced 7 to 10 more wet days than average for the time of year, some more.
Unusually, soil moisture surpluses exist in some North Island areas, and the west of the South Island. However, soil moisture deficits remain high in parts of central Marlborough, Canterbury, and Otago.
Temperatures were below normal. Sunshine totals were well below normal throughout the south and west of the North Island. However, sunshine was near normal in Canterbury and coastal Otago. The highest February 2004 temperature was 31.0°C, recorded at Alexandra on the 2nd. The lowest temperature for the month was -1.1°C, recorded at Manapouri on the 26th.
Of the four main centres, Dunedin was the driest. It was very wet in Auckland, Wellington and Christchurch. Temperatures were below average in all four centres. Sunshine hours were below normal in Auckland and Wellington, and near normal in Christchurch, and Dunedin.
Rainfall was four to six times of average February totals in much of the south and west of the North Island from Waikato to Wellington, including Wairarapa, and two to three times the monthly average in most other North Island regions, as well as Buller, north Westland, Marlborough and Nelson. Totals were also above average over much of the South Island.
Mean temperatures were as much as 2.5°C below normal in the Southern Lakes, Central Otago, and inland Canterbury, and below normal in most other regions. However, Hawke's Bay temperatures were above average. The February national average temperature of 16.1°C was 1.1°C below normal.
Thanks to NIWA
Contact for Enquiries
The Ministry of Agriculture and Forestry
Pastoral House
25 The Terrace
PO Box 2526, Wellington
Tel: 0800 00 83 33
Fax: +64 4 894 0720
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