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Spring 2001

Sunday 16 December 2001

A spring of extremes
5th warmest spring overall
Extremely wet in eastern Bay Of Plenty, Marlborough and Nelson

The spring of 2001 was one of the warmest on record, being the fifth warmest since reliable measurements began in the 1850s. It was a season of extremes, beginning with rather settled weather in September. However, unsettled conditions prevailed in many regions in both October and November, especially in central New Zealand, resulting in the wettest spring on record in parts of Marlborough and Nelson.

The national average temperature of 12.9°C was 0.8°C above the normal (1961–1990) spring temperature. Mean temperatures were 1.0°C or more above normal in many northern and western regions from Northland to Fiordland, as well as Nelson, Southern Lakes and Southland.

It was also very wet in eastern Bay of Plenty, and rainfall was above average in many coastal areas of the North Island. Contrasting drier than normal conditions occurred throughout the central North Island volcanic plateau and the Southern Lakes district of the South Island. The transition from drought to deluge in central New Zealand alleviated severe early spring soil moisture deficits in the north of the South Island, although high soil moisture deficits are still present in parts of inland Otago and South Canterbury.

Buller and Southland experienced above average sunshine hours, while less sunshine than usual prevailed in Bay of Plenty, Wellington, Marlborough and Canterbury.

Spring began with more frequent anticyclones (‘highs’) over central New Zealand in September. A marked change occurred after that, with the October and November climate patterns dominated by more frequent depressions (‘lows’) than average in the mid Tasman Sea, extending troughs of low pressure over northern and central New Zealand. Overall, these patterns acted to reduce the frequency of the normal spring westerly winds and resulted in more frequent northeasterlies over much of the country.

Extremely warm in the north, west, and south

Mean temperatures were 1.0°C or more above normal throughout much of Northland, Auckland, western regions from Waikato to Fiordland, as well as Nelson, Southern Lakes and Southland, and at least 0.5°C above normal in most other regions. Temperatures were near average in coastal Wairarapa.

Near or record high mean spring temperatures were recorded at:

Location Mean temperature (°C) Departure from normal Year records began Comments
Kaitaia Observatory 15.6 +1.1 1985 Highest
Dargaville 15.6 +1.7 1943 2nd highest
Whangarei Airport 15.8 +1.3 1967 2nd highest
Auckland, Owairaka 15.3 +1.2 1949 Highest
Auckland Airport 15.4 +1.0 1962 3rd highest
Pukekohe 15.0 +1.3 1970 Highest
Hamilton Airport 14.2 +1.3 1970 Equal highest
New Plymouth Airport 13.8 +1.1 1944 2nd highest
Ohakune 11.6 +1.3 1962 Highest
Wanganui 14.3 +1.0 1937 3rd equal highest
Palmerston North Airport 13.3 +1.0 1962 Equal highest
Wellington Airport 13.9 +1.1 1962 3rd equal highest
Farewell Spit 14.2 +1.5 1971 Equal highest
Westport Airport 13.1 +1.3 1937 3rd highest
Hokitika Airport 12.4 +1.2 1964 3rd highest
Milford Sound 11.4 +1.2 1935 3rd equal highest
Puysegur Point 11.4 +1.2 1981 Highest
Nelson Airport 13.4 +1.3 1943 2nd highest
Queenstown 12.1 +1.5 1871 Highest
Queenstown Airport 10.9 +1.2 1968 Highest
Lauder 11.3 +1.2 1981 2nd highest
Invercargill Airport 10.9 +1.0 1948 Equal highest
Tiwai Point 11.5 +1.1 1970 Highest
Raoul Island 18.8 +1.2 1940 2nd equal highest

Unusually wet in eastern Bay Of Plenty, Marlborough and Nelson

Rainfall was at least 150 percent of normal in eastern Bay of Plenty, Marlborough and Nelson, and at least 110 percent of normal in Northland, Coromandel, Gisborne, Taranaki, Wanganui, Wellington, and many other coastal areas of the North Island.

Near or record high spring rainfall was recorded at:

Location Spring rainfall (mm) Percentage of normal Year records began Comments
Whakatane Airport 435 156 1976 2nd highest
Whakatane 477 197 1947 3rd highest
Nelson Airport 385 152 1941 Highest
Blenheim 297 194 1930 Highest
Blenheim Airport 315 177 1941 Highest

Below average rainfall in the central North Island and southern lakes

Rainfall was less than 75 percent of normal in the central North Island volcanic plateau and the Southern Lakes district of the South Island, as well as isolated areas in southern Hawke’s Bay, and parts of south Canterbury.

Near record low spring rainfall was recorded at:

Location Spring rainfall (mm) Percentage of normal Year records began Comments
Ohakune 259 67 1961 3rd lowest

Sunny in Buller and Southland
Cloudy in Bay Of Plenty, Wellington, and many eastern areas

Sunshine and solar radiation totals were above average in Buller and Southland, and below average in Bay of Plenty, Wellington, Marlborough and Canterbury. Most other regions experienced near average sunshine hours.

Highlights

Extreme temperatures

  • The highest air temperature for the spring was 30.1°C, recorded at Darfield, on 30 November.
  • The lowest air temperatures for the spring was -5.5°C, recorded twice at Waiouru on 25 September and 25 October, and also at The Chateau, Mt Ruapehu on 25 October.

Significant rainfall and flooding

  • Heavy rainfall, with surface flooding occurred throughout Northland on 5 October, with rain as high as 25 mm in an hour, and temporary closure of a number of roads. Many sites in the region measured rainfall totalling between 75 and 100 mm in the 24 hours to 9 am on that same day. Heavy rainfall and surface flooding also occurred in the Auckland region.
  • High rainfalls resulted on 22 November, with totals from 50 to 100 mm throughout the Wellington-Hutt Valley region (where slips and surface flooding resulted, causing a few road closures and traffic delays). Water was knee-high on a Newlands Road. Much of the Wellington rainfall occurred within six hours.

Tornadoes

  • High winds occurred with the passage of a 100-metre-wide waterspout/tornado through Cable Bay, Northland, at about 12.30 pm on 9 October, resulting in damage to about 19 houses, some extensive. Another tornado was report on the same day at Mata, 22 km southeast of Whangarei, moving a barn 100 metres across a paddock.
  • Four tornadoes were sighted on 4 November at Awakeri, near Whakatane, one totally destroyed a hay-barn on a farm, just missing nearby residents.

High winds and rough weather

  • Squally north-westerlies with isolated thunderstorms and heavy rainfall affected many northern and western North Island regions, with the approach of an active cold front during the night of 31 October. Parts of Auckland appeared to be worst affected with fallen trees, and at least 10 houses having damaged roofs, associated with the passage of a ‘vortex’ and wind gusts to about 150 km/h. Fallen trees were also reported in Tauranga and Rotorua.
  • High winds and heavy rainfall buffeted the Gisborne region over the night of 22 October, resulting in extensive damage in kiwifruit orchards.
  • Storm-force southerlies buffeted Cook Strait, with wind gusts to 198 km/h at Baring Head on 17 November.

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.