April 2007

• Rainfall: Below normal in most regions
• Soil moisture: Significant deficits persist in Hawke’s Bay, central Marlborough and Central Otago
• Temperature: Below normal over much of the North Island
• Sunshine: Above average in many areas

April was a relatively dry month overall, especially over the North Island and the north and west of the South Island. It was an autumn like month, with anticyclones to the west and winds from the southerly sector producing cooler than normal conditions for many and plentiful sunshine with the dryness. Less than 50 percent (half) the normal rainfall was recorded in eastern parts of Northland, Taranaki, Gisborne, Horowhenua, and much of the west of the South Island. Rainfall at the end of the month meant significant soil moisture deficits (at least 110 mm) persisted only in Hawke’s Bay, central Marlborough and Central Otago. Temperatures were at least 0.5°C below average in many North Island areas, but near normal over much of the South Island. The national average temperature was 13.0°C, 0.5° below normal. April was a sunny month in many regions, apart from the south and east of the South Island, with record high April sunshine hours recorded at Kaitaia. Anticylones (‘highs’) were more very much frequent to the south of Tasmania, with depressions (‘lows’) often south of the Chatham Islands, resulting in more frequent southerlies than usual over New Zealand.

Other Highlights

• The highest temperature during April 2007 was 26.6 °C recorded at Hastings on the 1st. The lowest air temperature during the month was –3.1 °C recorded at Tara Hills, Omarama on the 12^th, and also at Ranfurly on the 30^th.
• High rainfall events, with at least 75 mm in 24 hours affecting Fiordland on the 10^th and 23^rd of April.
• Unseasonable snowfall occurred at Lake Rotoiti on the 14^th.
• Southwest gales with very high gusts, exceeding 130 km/h, were measured in parts of Auckland between the 12^th and 13^th of April, the highest being 146 km/h at North Shore on the 13^th.
• Auckland was the warmest and sunniest, and Dunedin the driest, of the five main centres. Rainfall was near normal in Wellington and Christchurch, and below normal in the other main centres. Temperatures were near normal in Auckland and below normal in the other main centres. Sunshine hours were above normal in Auckland and Wellington, near normal in Hamilton and Christchurch, and below normal in Dunedin.

Rainfall

Rainfall was 50 percent (half) or less of normal in eastern parts of Northland, Taranaki, Gisborne, Horowhenua, and much of the west of the South Island. Rainfall was less than 75 percent (three quarters) of normal in many other regions.

Temperature

Mean temperatures were at least 0.5 °C below average throughout much of the North Island, about 1.0 °C below average in parts of Hawke’s Bay, Wairarapa, and Manawatu, and near average over much of the South Island.

Sunshine

April sunshine hours and/or solar radiation were more than 110 percent of normal in many areas of New Zealand, except South Taranaki, Manawatu, and the east of the South Island from Southland to the Canterbury coast where they were near normal.

Full report

• Full details of the April 2007 Climate Summary

For further information, please contact:

Dr Jim Salinger – Principal Scientist, Climate NIWA National Climate Centre – Auckland Phone +64 9 375 2053 [email protected]

Stuart Burgess – Climatologist NIWA National Climate Centre – Wellington Phone +64 4 386 0569 [email protected]

Geoff Baird – Communications Manager Phone +64 4 386 0543 [email protected]

Acknowledgement of NIWA as the source is required.