October 2007

Stormy and generally cold with frequent spring gales

• Wind: Much more wind than normal, with frequent gales from the westerly sector
• Temperature: Well below average in the South Island and parts of the North Island, above average in Hawke’s Bay and parts of the north
• Rainfall: Above normal in many regions, especially in the South Island.
• Sunshine: Near or above normal in most regions

October 2007 was rather stormy and generally cold with deep depressions tracking south of New Zealand and frequent westerly gales. This was the equal 4th windiest October overall in regard to westerlies in measurements that commenced in 1966. Wind gusts over 130 km/h were recorded on 13 days (42%) in the month. In fact, many stations had at least 7 more days with strong winds (with gusts to 60 km/h or more) than is average for the time of year.

Temperatures were below average throughout much of the South Island, and the southern North Island. In contrast average or above average temperatures occurred in the north and east of the North Island. The national average temperature of 11.7 ºC was 0.5 °C below average.

Rainfall was almost 200 percent (twice) of normal in parts of north Westland, at Hanmer Forest, and inland parts of north Canterbury, and above normal in many other regions, especially in the South Island. Only in the Far North was rainfall about 50 percent (half) of normal. This produced soil moisture surpluses in Fiordland, Gisborne, and Wairarapa. Significant soil moisture deficits (more than 110 mm) occurred toward the end of the month in parts of Marlborough and Central Otago (normal for the time of year).

The month was much sunnier than usual in Northland, Gisborne, north Canterbury, Otago, and Southland

Further Highlights

• The lowest air temperature during the month was -6.2 ºC recorded at Waiouru AWS on the 4^th.
• The highest temperature during October 2007 was 27.2 ºC recorded at Timaru Airport on the 30^th.
• Surface flooding occurred in the Hutt Valley on the 7^th. Days of high rainfall resulted in an overflow of the Waiau River (in North Canterbury) on the 8^th, and heavy rainfall occurred in the central North Island, with 30 mm recorded at Ohakune in an hour on the 17^th.
• Snowfall occurred in many high country areas over 2-7 October, 10-11, 14-15, and 17-18 October.
• High winds from the west and northwest were more frequent than normal, with gale force events on 4 and 23 October resulting in fallen trees, broken power lines, and difficulty for motorists, in several regions. In the south, such high winds occur very infrequently.
• Of the five main centres, Auckland was the warmest, Wellington the wettest, and Christchurch the driest and sunniest.

Temperature

Mean temperatures were well below average in inland areas of the South Island and Southland, with one of the coldest October’s on record. It was also below average in most other South Island regions, as well as Wellington. In contrast they were above average in Northland, Coromandel, Gisborne, and Hawke’s Bay.

Rainfall

Rainfall was almost 200 percent (twice) of normal in the central North Island, parts of north Westland, at Hanmer Forest, and in inland parts of north Canterbury. Totals were also above normal in parts of Auckland, Gisborne, Wairarapa, Kapiti, Wellington, Buller, Marlborough, Nelson, the Southern Lakes district, Otago, and Southland. Rainfall was less below normal in much of Northland, parts of Bay of Plenty, and in Hawke’s Bay.

Sunshine

Sunshine hours were above normal in the north and east of both islands, especially Northland, Gisborne, north Canterbury, Southland, and Otago. Sunshine was near normal elsewhere.

Full report

• Full details of the October 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.