Winter 2008

Winter 2008: Very stormy and wet with floods and snow to low levels.

• Rainfall: Well above normal for north and west of North Island and eastern South Island
• Temperature: Above average in the north and west, below average in coastal Otago
• Sunshine: Above normal for much of the North Island, Fiordland and Southland

Winter 2008 was very wet and stormy in many areas, with frequent extremes. Significant flood-producing rainfall events occurred in Northland, Coromandel, and the Bay of Plenty, and twice in Marlborough. Wanganui, Manawatu, Marlborough, and parts of the central Plateau and Wellington had their wettest winters on record. Damaging windstorms occurred in the north of the North Island and August snow storms fell to unusually low levels in some places. In contrast, winter was comparatively benign in South Westland and Fiordland.

Winter rainfall was over 200 percent (double) of normal in Marlborough and Canterbury and about 150 percent (one and a half times) normal in Auckland, Waikato, Bay of Plenty, Taranaki, Manawatu, Wellington, northern parts of the Southern Alps, and coastal Otago. Not only were the rainfall totals far above normal for these locations, the number of days with rain was also much higher than average, particularly during July (23 days of rain in Kaitaia and New Plymouth, 22 in Auckland and Pukekohe, and 20 in Wellington). Gisborne, Hawkes Bay and Westland received about normal rainfall for winter, while parts of Fiordland and central Otago received about 75 percent (three quarters) of normal rainfall.

Winter overall was slightly warmer than average in parts of northern New Zealand, central Otago and Fiordland, and below average in eastern Otago and the Wairarapa. The national average temperature of 8.5 °C was 0.2 °C above average for winter. June saw a mild start to winter with much warmer than average conditions in many places especially inland South Canterbury and Otago, with temperatures 1.5 to 2°C above average. Average daily maximum temperatures during June were between 2 and 3 °C above average in these same areas. July was also generally warmer than average overall, and only slightly cooler than June, despite a cold spell which saw frosts as far north as Auckland and -9.1°C in Waiouru (a record low July minimum temperature for this location) in the second week of the month. August temperatures were near average in the North Island but below average in the South Island. The three days from the 9^th to the 11^th were particularly cold for many locations, with minimum temperatures as low as -5.0°C recorded at Dunedin Airport, -4.0°C at Martinborough and 1.5°C at Kaitaia (all August records). The overall winter climate pattern was dominated by more depressions (‘lows’) crossing central New Zealand and often centred to the east, with more frequent south easterly flows over the southern South Island, and westerlies over the North Island.

Major highlights

• Winter produced several high rainfall/flood-producing events. On 26 July heavy rainfall in Northland and Coromandel (166 mm was recorded in Paeroa, the highest ever 1-day total for July since 1914) caused severe flooding. A few days later on 29 July, heavy rainfall caused more flooding, slips and damage in Thames/Coromandel, Auckland, Nelson and Marlborough, with a North Shore home completely destroyed by a slip and another 14 homes at risk.
• More severe flooding occurred on 26 August, when 126 mm of rain fell in the 24 hours to 9am on the 26th at Kaikoura (the second highest 1-day August rainfall for this location since 1898) resulting in several landslides, damage and death of many livestock.
• The highest temperature during winter 2008 was 23.1°C recorded at Waipara West on the 15^th of June. This was only 0.9°C below the record South Island temperature for June of 24.0°C recorded at Kaikoura and Temuka on 2 June 1976.
• The lowest temperature during winter was recorded at Arthurs Pass on the 20^th of August, where the minimum temperature was -9.5°C. In July, there were freezing temperatures across the country on the 9^th, with negative numbers recorded from Auckland (-1°C) to Queenstown (-4°C). The unusual sight of frost in Auckland was seen for two days in a row on the 8^th and 9^th.
• Windstorms struck Northland and Auckland on 26 July bringing down powerlines and trees, leaving 53,000 homes without power in the Auckland region.
• There were two major snowfall events in winter. The first occurred on 15 August bringing snow to unusually low levels in the north west of the South Island. Three days later on 18 August, snow fell to very low levels in the North Island, with over 1 m of snow at Ruapehu village.
• Of the five main centres, Auckland was the warmest, Wellington the wettest and sunniest, and Dunedin was the driest. Winter temperatures were near or slightly above average at all five locations. Rainfall was well above normal in Auckland and Christchurch, above normal in Hamilton and Wellington, and near normal in Dunedin. Winter sunshine was near normal everywhere.

Rainfall

Winter rainfall was over 200 percent (double) of normal in Marlborough and Canterbury and about 150 percent (one and a half times) normal in Auckland, Waikato, Bay of Plenty, Taranaki, Manawatu, Wellington, northern parts of the Southern Alps, and coastal Otago. Gisborne, Hawkes Bay and Westland received about normal rainfall for winter, while parts of Fiordland and central Otago received about 75 percent (three quarters) of normal rainfall.

Temperature

Seasonal mean temperatures were about 0.5 °C above average in western parts of Northland, Taranaki and Fiordland and more than 1.0 °C above average in parts of Central Otago. They were below average by about 0.5°C in the southeast of the North Island and eastern Otago.

Sunshine

Winter sunshine hours were at least 110 percent of normal in Northland, Waikato, Bay of Plenty, Gisborne, Hawkes Bay, Wellington and southwestern South Island. In Taranaki, Manawatu, Westland and coastal Otago totals were lower than usual, being 90 percent of normal.

Full report

• Winter 2008 climate summary (PDF 144 KB)

For further information, please contact:

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

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

Michele Hollis – Communications Manager Phone +64 4 386 0483 [email protected]

Acknowledgement of NIWA as the source is required.