August 2007

• Rainfall: Below normal in the north and east of the South Island, near or above normal in regions exposed to the west
• Temperature: Above average in the North Island, near average elsewhere
• Sunshine: Well above average in Wellington, Nelson, and inland South Canterbury
• Wind: More southwesterlies than normal; northwest gales during the second week

August 2007 was a month which was windy at times with frequent disturbed southwesterlies, especially to the east, resulting in low rainfall in sheltered northern and eastern South Island regions, and normal or above normal rainfall in several other regions.

Rainfall was less than 33 percent (a third) of normal in southern parts of Marlborough, on Banks Peninsula, and inland parts of Otago, with soil moisture levels now below normal for the time of year in some of these regions. Temperatures were above normal over much of the North Island and near average over much of the South Island. The national average temperature of 9.1 °C was 0.4°C above normal. The month was particularly sunny in Wellington, Nelson, and inland areas of south Canterbury. August’s climate patterns were produced by more frequent depressions (‘lows’) south of the Chatham Islands, more anticyclones (‘highs’) in the Tasman Sea, resulting in frequent southwesterly winds over New Zealand. Three depressions tracked across New Zealand during the month (on the 5^th, 17^th, and 27^th).

Further Highlights

• The highest temperature during August 2007 was 22.2 °C recorded at Dunedin Airport on the 31^st, their highest on record for August.
• The lowest air temperature during the month was -8.4 °C recorded at Hanmer Forest on the 20^th. A grass minimum of -16.4 °C was recorded at Mt Cook Village on the 15^th, their lowest on record for August.
• High rainfall at Milford Sound totalled 431 mm over the 96 hours (4–days) to 9am on the 12^th, and 107 mm at Kerikeri Airport over the 24 hours to 9am on the 17^th.
• Gale force northwesterlies buffeted many central and southern New Zealand regions over the 10^th -12^th, with several power lines damaged in parts of Otago.
• Of the five main centres, Auckland was the warmest, Dunedin the driest, Christchurch the coldest, Hamilton the wettest, and Wellington the sunniest.

Rainfall

Rainfall was less than 50 percent (half) of normal in many eastern regions from southern Wairarapa to Otago, as well as Nelson. However, rainfall totals were near or above normal in many regions exposed to the west, being at least 125 percent (one and a quarter) of normal in parts of Northland, Waikato, Manawatu, Wanganui, and the west of Southland.

Temperature

Mean temperatures were about 1.0 °C above average over much of the North Island, central Marlborough and Nelson, and some inland areas of the South Island, and near average elsewhere. The national average temperature was 9.1 °C (0.4 °C above normal).

Sunshine

August sunshine hours and/or solar radiation were at least 120 percent of normal in Nelson, Wellington, and inland South Canterbury, and more than 110 percent of normal in Marlborough, north Canterbury, and East Otago. Sunshine hours were below normal in Manawatu and near normal elsewhere.

Full report

• Full details of the August 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.