July 2006

• Rainfall: Very wet in Wairarapa, Wanganui, and Wellington (landslips and severe flooding in some areas); extremely dry in parts of Northland, Auckland, and parts of Otago
• Temperature: Above average in the east of the North Island, Marlborough, Nelson, and Southern Lakes; below average in Northland, inland South Canterbury, and North Otago
• Sunshine: Very sunny in the north and west of the North Island, as well as inland South Canterbury and coastal Otago

July was warmer than June (by 0.8 °C). This happens on average once in five years, and this year provided a reprieve from the very cold start to winter. In fact, overall this July temperatures were slightly above average. The national average temperature of 8.2 °C was 0.3 °C above the 1971-2000 normal. July 2006 temperatures were above average in the east of the North Island, Marlborough, Nelson, and Southern Lakes, and below average in Northland, inland South Canterbury, and North Otago.

An active low produced landslips, flooding and high rainfall in July in Wairarapa, and parts of Wanganui and Wellington during the first week of the month. Rainfall for the month was more than twice normal in Wairarapa (in some places it was the wettest July in more than 30 years), and more than one and a half times normal in King Country, Wanganui, Hawke’s Bay, and Wellington (including the Kapiti coast). In contrast, July was rather settled in other areas with rainfall totals a mere 25 percent (a quarter) or less of normal in parts of Northland, and North Otago, and 50 percent (half) or less of normal in Auckland, Coromandel, Central and East Otago.

July was much sunnier than normal in the north and west of the North Island, as well as inland South Canterbury, and coastal Otago.

More anticyclones ('highs') in the Australian Bight extended over New Zealand producing more south easterlies to the north, with westerlies and southwesterlies to the south of the country.

Other Highlights

• The highest temperature during July 2006 was 20.2 °C recorded at Whakatu, Hastings, on the 31st. The lowest air temperature for the month was -12.2 °C recorded at Lake Tekapo on the 6th. Minimum air temperatures were -10 °C or lower in parts of inland South Canterbury/North Otago on the 1st, 5th, 6th, and 7th of July.
• A wind gust of 148 km/h was recorded at Rock and Pillar, Otago on the 22nd, and 146 km/h at Mt. Kaukau, Wellington on the 5th. Tornados destroyed property in the Waikato on the 12th.
• Severe flooding and landslips occurred after high rainfall from 4-6 July in the Wairarapa, Wanganui and Wellington regions. 100 mm was reported within 24 hours in parts of South Wairarapa, where people had to be evacuated from their homes. Martinborough was isolated by floodwaters, and surface flooding which also affected Greytown and Carterton. In Wairarapa, more than 50 roads were closed due to flooding or landslips. The settlement of Mangamahu (northeast of Wanganui) was isolated by the collapse of the Mangawhero river bridge. A house in Wanganui was struck by a landslide, with two others later affected in Hunterville. On 21 July, an Eastbourne house became perched above a landslide.
• Snowfall closed the Desert Rd on the 6th, with many skiers stranded on Mt. Ruapehu. Showers of sleet and snow fell to low levels in the lower North Island on the 21st, and settled in the Queenstown area; and closing Queenstown airport.
• Dunedin was the driest, Wellington the wettest, Auckland the sunniest, and Christchurch the coldest of the main centres. Rainfall was well above average in Wellington and below average in all four other main centres. Temperatures were above average in Wellington Dunedin, below average in Auckland, and near average in the other main centres. Sunshine totals were above average in all five main centres.

Rainfall

Rainfall was more than 200 percent (twice) of normal in Wairarapa, and more than 150 percent (one and a half) of normal in King Country, Wanganui, Hawke’s Bay, and Wellington (including the Kapiti coast). It was also wet in Manawatu, and scattered areas of Canterbury. In contrast, July rainfall totals were 25 percent (a quarter) or less of normal in parts of Northland, and North Otago, 50 percent (half) or less of normal in Auckland, Coromandel, Central and East Otago. Rainfall was also below normal in Bay of Plenty, Buller, Westland, Marlborough, South Canterbury, and West Otago.

Temperature

Mean temperatures were generally near average over the country. However, they were above average in the east of the North Island, Marlborough, Nelson, and Southern Lakes. In contrast, temperatures were below average in Northland, inland South Canterbury and North Otago.

Sunshine

Sunshine hours and/or solar radiation were at least 120 percent of normal in parts of Northland, Auckland, Taranaki, Wellington, inland South Canterbury, and coastal Otago, and about 110 percent of normal in Waikato, Manawatu, and Nelson.

Full report

• Full details of the July 2006 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.