Niwa National Climate Centre
Tuesday 1 September 2009

National Climate Summary – August 2009: An early start to spring!

• Temperature: The warmest August on record, with record temperatures at many locations.
• Rainfall: Well above normal rainfall in Westland, and in parts of Fiordland and Waikato; very dry in eastern parts of both islands.
• Sunshine: Sunshine totals were well above normal over the lower North Island, but well below normal in Fiordland, Westland and in the far north.

It was an early start to spring, with temperatures rocketing upwards during August to record or near-record levels over much of the country. Temperatures were more than 2°C above average in central Otago and the Lakes District, and parts of: Canterbury, Northland, Auckland, and the western Bay of Plenty. Well above average temperatures (between 1.2°C and 2°C above average) were recorded elsewhere, except for Gisborne and Hawke’s Bay (with temperatures between 0.5°C and 1.2°C above average). It was the warmest August since records began 155 years ago, with a national average temperature of 10.2°C (1.7°C above the long-term August average).

Well above normal rainfall for August (more than 150 percent of normal) occurred in Westland and parts of Fiordland and the Waikato. Rainfall was also above normal in Nelson/Marlborough (between 120 and 150 percent of normal). In contrast, well below normal August rainfalls (less than 50 percent of normal) were recorded in coastal parts of the Wairarapa, southern Hawkes Bay and Gisborne, coastal Canterbury and parts of Otago. Below normal August rainfall (between 50 and 80 percent of normal) occurred in Northland and Auckland. Elsewhere, August rainfall was near normal.

August 2009 was a very sunny month in the lower North Island (Wellington, Kapiti Coast, Manawatu/Horowhenua, the Wairarapa and southern Hawkes Bay), with August sunshine totals greater than 125% of normal. In contrast, well below normal August sunshine totals (less than 75 percent of normal) were recorded in Fiordland, Westland and Kaitaia. It was a sunny month for the east of the South Island.

There were three notable weather events during August: On the 1st and 2nd of the month, trees and deep snow from a series of avalanches blocked the only road access to Milford Sound (via the Homer Tunnel), until the 11th. Thunderstorms on the 26th brought heavy rain and lightening to Taranaki, Auckland and the western Bay of Plenty (cutting power to more than 8000 homes). On the 31st, heavy rain resulted in surface flooding across the greater Wellington region, causing a major slip onto the railway tracks at Pukerua Bay.

During August 2009, frequent northerly winds affected New Zealand, resulting in warmer temperatures.

Further Highlights:
• The highest temperature during August 2009 was 25.5°C recorded at Henderson (Auckland) on the 11th. The lowest temperature was recorded at Dashwood (Marlborough) with a minimum temperature of -8.6°C on the 18th.
• The highest 1-day rainfall total for August was 260.4 mm, recorded at Awakino (coastal Waitomo) on the 25th.
• The highest wind gust for August was 165 km/hr recorded at both Cape Turnagain (Wairarapa Coast) and Awakino (coastal Waitomo) on the 28th and 29th, respectively.
• Of the six main centres, Auckland and Tauranga were the warmest; Wellington was the sunniest and also the wettest, Dunedin the driest, and Christchurch the coolest.

TEMPERATURES: A RECORD WARM AUGUST, WITH WELL ABOVE AVERAGE TEMPERATURES IN MANY LOCATIONS

It was the warmest August since records began 155 years ago, with a national average temperature of 10.2°C (1.7°C above the long-term August average). This was a remarkable turn-around after the unusually cold months earlier in the winter. Mean temperatures were more than 2°C above average in central Otago and the Lakes District, and parts of: Canterbury, Northland, Auckland, and the western Bay of Plenty. Well above average temperatures (between 1.2°C and 2°C above average) were recorded elsewhere, except for Gisborne and Hawke’s Bay (with temperatures between 0.5°C and 1.2°C above average).

Record high monthly maximum temperatures were experienced at numerous locations across New Zealand, and notably, maximum temperatures in August 2009 were 3.0°C above August average at Cromwell (central Otago) and Waipara West (Canterbury), and 4.0°C above August average at Hanmer Forest (Canterbury).

ENDS

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