Spring 2006

Spring 2006: Distinctive El Niño spring with blustery westerlies and south westerlies; very windy at times with stronger than usual east/west contrasts in climate.

• Rainfall: Dry in Northland, coastal Bay of Plenty, Gisborne, Hawke’s Bay, and eastern Otago; wet in the southwest of the North Island, and the west and far south of the South Island
• Temperature: Warm in the east of the North Island and Marlborough; temperatures near normal elsewhere
• Sunshine: Sunny in the northeast of the North Island and southeast of the South Island, rather cloudy in the west of the North Island

Classic El Niño weather patterns produced a spring with many days of westerly gales over the country, with marked contrasts in climate between western and eastern areas. Significant windstorms occurred in some part of New Zealand on at least ten separate occasions, with blustery conditions on many others. Western areas of the North Island and the west and far south of the South Island had very stormy conditions at times whilst the Bay of Plenty, Gisborne and Hawke’s Bay were relatively dry, sunny and mild.

Windstorms particularly in October and November produced one of the windiest springs in the South Island and southern North Island in the past two decades, with the loss of one life and damage to property including blowing down forest trees. Spring rainfall was only 50 to 75 percent (half to three quarters) of normal in Northland, coastal Bay of Plenty, Gisborne, Hawke’s Bay, and east Otago, with significant soil moisture deficits developed in Gisborne, Hawke’s Bay, coastal Marlborough and coastal Bay of Plenty by the conclusion of spring. In contrast spring rainfall was 125 to 150 percent or normal from Manawatu to Wellington, parts of the Southern Lakes and Fiordland. Sunshine showed similar east/west patterns with extremely high values in parts of the southeast of the South Island, and low totals in the west of the North Island from Taranaki to Wellington. The national average temperature for spring of 12.3°C was slightly warmer than normal, being 0.3°C above average. Spring temperatures were particularly mild in Gisborne, Hawke’s Bay and Marlborough and parts of central Canterbury where these were up to 1°C above average. These patterns were produced by lower pressures than normal to the south and south east of New Zealand, and higher pressures over the north, resulting in much more frequent westerly winds than normal. These produced the drying hot foehn westerly winds in the east, with frequent rain days in the west, and pushed Lake Wakatipu towards flood levels by the end of November.

Major Highlights

• The highest temperature during spring was 30.4 °C recorded at Gisborne Airport on the 13th October. Near or record high September air temperatures were recorded in Dunedin Airport (24.9 °C), Invercargill (23.1°C) and Queenstown (24.3 °C) on the 25th, and at Gisborne (24.9 °C) on the 26th September.
• The lowest air temperature for spring was -5.6 °C recorded at Hanmer Forest on the 11th September.
• High rainfall events were very frequent throughout spring in Fiordland, parts of the Southern Lakes, and Arthur’s Pass on about 20 occasions, and high rainfall events occurred in Auckland, Taranaki, Wellington and Golden Bay. Surface flooding occurred in the Wairarapa, and in Wellington during Labour weekend.
• Severe weather on 1 October produced high winds, attributed to tornadoes or waterspouts, which damaged trees and property in West Auckland. Heavy rainfall and widespread surface flooding occurred on the same day in parts of Auckland City.
• A wind gust of 180 km/h from the northwest was recorded at Southwest Cape (Stewart Island) on the 2nd September, a new record for a wind gust at that site (measurements commenced in 1992). Windstorms were very frequent, with southerly gales occurring through Cook Strait and Wellington on 4th, 5th and 24th of October, disrupting sea and air transport. The many more days of strong or gale force westerly quarter winds produced fallen trees and power lines on 9/10 November in Auckland and Bay of Plenty, and felled trees in North Canterbury on 14 November killing one person.

Of the five main centres, spring was especially pleasant in Dunedin. Dunedin again was easily the driest, and Wellington the wettest. Christchurch was the sunniest. Rainfall was above average in Auckland, Wellington and Christchurch, below average in Hamilton and well below average in Dunedin. Temperatures were above average in Dunedin and below average in Wellington. Spring sunshine totals were above average in Christchurch, and well above average in Dunedin. These were below average in Hamilton and Wellington.

Rainfall

Spring rainfall was less than 75 percent (three quarters) of normal in eastern Northland, Coromandel, Bay of Plenty, Gisborne, northern Hawke’s Bay, and East Otago. Rainfall was near normal elsewhere. Rainfall was at least 125 percent (one and a quarter) of normal in Manawatu, Horowhenua, Kapiti, South Westland, Queenstown area and coastal Southland.

Temperature

Seasonal mean temperatures were slightly above normal for New Zealand overall. These were nearly 1°C above normal in the east of the North Island. They were 0 to 0.5°C in most other areas, and close to average in the west and south of the South Island.

Sunshine

Sunshine totals in spring were at least 110 percent of normal in Gisborne, and from Canterbury to Southland. However, 90 percent or less of normal occurred in the west of the North Island, especially in Manawatu. Gisborne and Dunedin recorded their third sunniest spring on record.

Full report

• Full details of the Spring 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.