Climate Summary for April 2009

April 2009: A month of contrasts. Wet in the north and west, dry in the south and east.

April 2009: A month of contrasts. Wet in the north and west, dry in the south and east. Cool in the north and east, warm in the south and west

  • Rainfall: Above normal rainfall in Northland and the West Coast; very dry throughout the eastern half of the North Island (particularly southern Hawke’s Bay and northern Tararua District); dry in coastal Canterbury, eastern Otago and along the south coast.
  • Sunshine: Below normal in Northland and Auckland; above normal in parts of Hawke’s Bay, Tararua District, Tasman District and Southland; near normal elsewhere.
  • Temperature: Below average over much of the North Island (especially central and eastern areas); above average in the south and west of the South Island..

Exceptionally low rainfall for April (less than 20 percent of normal) occurred in southern Hawke’s Bay and Tararua District. This has resulted in significant soil moisture deficits (more than 50 mm below normal levels) throughout this region. Other eastern areas of both islands, around Auckland, and along the south coast of the South Island received below normal rainfall (between 20 and 60 percent of normal) in April. Above normal rainfall (greater than 200 percent of normal, or “double”) for April was recorded in Northland and parts of the West Coast and Southern Alps.

Temperatures were below average (by between 0.5 and 1.5 °C) over most of the central and eastern parts of the North Island for April. In contrast, parts of the West Coast, coastal Fiordland, Southland and south Otago were warmer than average by between 0.5 and 1.5 °C. The national average temperature of 13.4°C was 0.1°C above the long-term average for April.

Well above normal sunshine totals for April (greater than 125 percent of normal) were recorded in Hawke’s Bay, Tararua District, Tasman District, and Southland. The north of the North Island (Northland, Auckland and the Coromandel Peninsula) received below normal sunshine (less than 90 percent of normal) for the month.

The most significant extreme weather event to impact on the country in April was on the 27th when heavy rain along the West Coast resulted in flooding. Homes were evacuated in Greymouth and roads became impassable. Trampers were stranded in the Mueller Hut in Aoraki Mt Cook National Park, and about 120 people were evacuated from the Milford Track by helicopter.

April 2009 was dominated by the persistence of anticyclones (“highs”) to the east of the North Island of New Zealand. This pattern resulted in more northerly air flows than normal over New Zealand, which contributed to the higher than normal rainfall in the north and west and the lower than normal rainfall in the east and south.

Further highlights

  • The highest temperature during April 2009 was 28.0°C recorded at Alexandra on the 16th and at Hororata on the 27th. The lowest temperature during April was recorded at Ranfurly on the 21st, where the minimum temperature was -6.2°C.
  • The highest 1-day rainfall total for April was 341 mm recorded at Mt Cook on the 27th (the highest April 1-day total for this location, since records began in 1928).
  • The wind gust of 165 km/hr recorded on Secretary Island (Doubtful Sound, Fiordland) on the 25th was the highest gust for April for New Zealand.
  • Of the six main centres, Tauranga was the warmest and sunniest, Auckland was the driest and Wellington was the wettest.

Full report

Full details of the April 2009 Climate Summary

Climate statistics tables

Climate statistics April 2009

For further information, please contact:

Dr Andrew Tait – Climate Scientist NIWA National Climate Centre – Wellington Phone +64 4 386 0562 Mobile +64 27 327 7948 [email protected]

Dr James Renwick – Principal Scientist NIWA National Climate Centre – Wellington Phone +64 4 386 0343 Mobile +64 21 178 5550 [email protected]

Acknowledgement of NIWA as the source is required.

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