Autumn 2001

Wednesday 13 June 2000

An autumn of extremes
Record low rainfall in Wellington and the east of the South Island
Very wet in Northland, Coromandel and Bay Of Plenty
Extremely sunny in central New Zealand
Warm in many areas

A fresh New Zealand record low 3–month rainfall total at Cape Campbell, coastal Marlborough, and an all time high rainfall for a non-alpine area, Leigh, in Northland, highlighted an autumn of climate extremes. Rainfall at Cape Campbell amounted to only 9 mm between 1 January, and 31 March, and its six–monthly total from 1 November to 30 April was 52 mm – an all time record for a six-month period anywhere in New Zealand. There was more than twice as much rainfall – 109 mm – in one hour at Leigh on 30 May, a new record for a non-mountainous area of the country. Overall, autumn featured droughts, floods and mean temperatures above average through most areas.

Extremely low autumn rainfall occurred throughout Wellington, Marlborough, Canterbury and coastal Otago, where rainfall ranged from 25 to 50 percent of normal. Wellington had its driest autumn in more than a century, while most of the extremely dry South Island areas experienced their driest autumn in more than 50 years. The dry conditions in these regions produced severe soil moisture deficits throughout much of the season. In contrast, autumn was rather unsettled and very wet in many areas north of Auckland and Bay of Plenty, as well as Coromandel (where autumn rainfall totalled 934 mm at Waihi, almost half the town’s annual amount). It was also wetter than usual in Auckland and coastal Southland.

It was extremely sunny in Wellington, Nelson, Buller and Westland, and also sunnier than average over much of the remainder of the South Island, as well as other southwestern North Island regions. Numbers of hours of bright sunshine were below average in Bay of Plenty and Gisborne.

Mean temperatures were about 0.5°C above normal throughout much of New Zealand. Near normal temperatures occurred in the east of the North Island, Westland, Fiordland, inland south Canterbury, and coastal Otago. The national average temperature for autumn of 13.6°C was 0.4°C above normal.

More frequent depressions (‘lows’) occurred in the north Tasman Sea. These produced warm moist northeasterlies on to the north of the North Island. At the same time, more anticyclones to the south and east produced the very dry conditions in the sheltered areas further south.

Extremely dry in Wellington and the east of the South Island

Extremely low autumn rainfall occurred throughout Wellington, Marlborough, Canterbury and coastal Otago, where rainfall ranged from 25 to 50 percent of normal. Wellington experienced its driest autumn in more than a century, while most other areas within these regions experienced their driest autumn in more than 50 years. Other regions with below average rainfall were Taranaki, Hawke’s Bay, Wairarapa, Nelson, and the South Island west coast, with totals between 50 and 75 percent of normal.

Near or record low autumn rainfall was recorded at:

Location Rainfall (mm) Percentage of normal Year records began Comments
Palliser 97 33 1930 Lowest
Wellington, Kelburn 124 38 1862 Lowest
Wellington Airport 83 32 1960 Lowest
Wallaceville 117 36 1924 Lowest
Takaka, Kotinga 286 50 1971 2nd lowest
Blenheim 59 40 1930 Lowest
Blenheim Airport 60 31 1941 Lowest
Hanmer Forest 115 38 1905 2nd lowest
Kaikoura 62 24 1949 Lowest
Winchmore 63 32 1947 Lowest
Christchurch Airport 62 37 1944 Lowest
Lincoln 50 29 1881 2nd lowest
Timaru Airport 62 40 1957 3rd lowest
Waimate 49 27 1898 2nd lowest
Dunedin Airport 74 43 1963 Lowest

Very wet in Northland, Coromandel and Bay Of Plenty

The autumn was rather wet and unsettled in many areas north of Auckland, as well as Coromandel and Bay of Plenty, where rainfall ranged from 125 to more than 200 percent of normal. It was also wetter than usual in Auckland and coastal Southland, with rainfall at least 115 percent of normal.

Near or record high autumn rainfall was recorded at:

Location Rainfall (mm) Percentage of normal Year records began Comments
Warkworth 592 168 1972 2nd highest
Whitianga Airport 708 158 1988 2nd highest
Whakatane 550 222 1992 Highest

Rainfall was near average over much of the central North Island.

Extremely sunny in central New Zealand

It was extremely sunny in Wellington, Nelson, Buller and Westland, with totals at least 115 percent of normal. It was also sunnier than average over much of the remainder of the South Island, as well as in Taranaki, Wanganui, Manawatu and Wairarapa, with totals at least 105 percent of normal.

Near record high autumn sunshine was recorded at:

Location Sunshine (hours) Percentage of normal Year records began Comments
Wellington 557 120 1928 3rd highest
Nelson Airport 656 117 1949 2nd highest
Arapito, Karamea 508 126 1980 2nd highest
Hokitika Airport 507 121 1964 3rd highest

Hours of bright sunshine were below average in Bay of Plenty and Gisborne.

Warm in many areas

Mean temperatures were about 0.5°C above normal throughout much of New Zealand. Near normal temperatures occurred in the east of the North Island, Westland, Fiordland, inland south Canterbury, and coastal Otago.

Highlights

Temperature

  • The highest autumn air temperature was 31.1°C, recorded in Christchurch Gardens on 25 March. The highest autumn air temperature on record for this location is 34.4°C.
  • The lowest air temperature for autumn was -9.6°C, recorded at Middlemarch, Otago, on 31 May. The lowest autumn air temperature on record in this area is -10.5°C

High rainfall and flooding

  • The remnants of tropical cyclone ‘Sose’ produced high rainfall in the Bay of Islands, Coromandel, and Bay of Plenty over the night of 12/13 April. Significant surface flooding resulted in Keao, where rainfall totalled 200 mm in less than 18 hours, and at Whitianga, where 132 mm was measured in 24 hours.
  • High-intensity rainfall resulted within a few hours in widespread surface flooding, and created chaos for Auckland traffic on 2 May. In places on the Southern Motorway, water was as high as car bonnets, bringing traffic to a stop. Rainfall totalling 30 mm was recorded at Whangaparoa in the hour to 5 pm.
  • Heavy rainfall and surface flooding occurred on 12 May in Auckland, the Nelson�Takaka, and eastern Bay of Plenty�Opotiki/Ohopi areas (where rainfall as high as 60 mm in 3 hours was reported).
  • Extreme high-intensity rainfall, record breaking for a non-alpine area of New Zealand, occurred at Leigh (north of Auckland) on 30 May. Torrential rainfall totalling 109 mm was measured in just one hour (between 1.30 and 2.30 am), superseding the previous New Zealand record for a one-hour event of 107 mm measured at Whenuapai on 16 February 1966. There was widespread damage to local roads and problems with drainage systems, and water flowed in torrents over an already saturated ground surface.

Tornado and high winds

  • A tornado, with severe winds, passed through part of Greymouth at about 4 am on the morning of 28 March. Several houses and garages were badly damaged by the wind and flooded by heavy rainfall accompanying the tornado.
  • High winds from the northwest gusted to 143 km/h in Kaikoura over the night of 28/29 March, damaging power lines and resulting in loss of electricity to more than 300 houses. An injured passenger was airlifted from a boat in Foveaux Strait in rough conditions on the same night.
  • High winds buffeted western Bay of Plenty over the night of 4/5 May, with a tree uprooted and power lost to parts of Tauranga. One house lost part of its roof.

Early snowfall to low levels: 21–27 May

  • Waves of unseasonably cold southerlies from polar latitudes swept onto southern New Zealand, bringing hail and snow to sea level throughout Southland, and onto the south Otago high country from the afternoon of 21 May. Snowfall continued on the 22nd, lying to a depth of 2 cm along the coast and 8 cm in some inland areas. The cold blast continued on the 23rd, with snowfalls spreading north to the Dunedin hills, Westland and Banks Peninsula. Snowfall to 2.5 cm was measured at Okarito, Westland, an event unheard of before in that area. Snow depths to 5 cm were reported in the Catlins and as much as 20 cm in inland Southland and the Otago high country. Further snowfall occurred in parts of Central Otago on the 27th.

For further information, please contact:

Dr Jim Salinger – Principal Scientist, Climate
NIWA National Climate Centre – Auckland
Phone +64 9 375 2053
j.salinger@niwa.co.nz

Stuart Burgess – Climatologist
NIWA National Climate Centre – Wellington
Phone +64 4 386 0569
s.burgess@niwa.co.nz

Geoff Baird – Communications Manager
Phone +64 4 386 0543
g.baird@niwa.co.nz

Acknowledgement of NIWA as the source is required.