Another Summer Of Extremes

EXTREMELY DRY IN CENTRAL NEW ZEALAND, WET IN BAY OF PLENTY

COOL IN THE SOUTH, WARM IN AUCKLAND, BAY OF PLENTY AND CENTRAL NEW ZEALAND

NELSON SETS NEW NEW ZEALAND SUMMER SUNSHINE RECORD

A 2000/2001 summer of climate extremes including droughts, floods and high humidity produced in Nelson a new seasonal sunshine record of 878 hours, 20 percent above normal and a new high for any New Zealand locality since such records began in 1930. Sunshine totals in Marlborough, Buller and north Canterbury were also at least 10 percent above normal. The national average temperature for the past summer of 16.8°C was 0.2°C above normal.

The extremely dry conditions in central New Zealand – the third driest summer conditions in parts of this region in 140 years of record keeping - produced severe soil moisture deficits and very high fire risk in Wellington, Nelson, Marlborough and Canterbury by the end of summer. In contrast it was frequently wet in the north east of the country.

The warm, dry and sunny conditions throughout central New Zealand resulted from more frequent highs (anticyclones) in the Tasman Sea, and ridges well to the east of the Chatham Islands. At the same time more lows (depressions) north east of Northland caused the warm, wet and humid conditions in the north east. More frequent westerlies to the south of the country kept temperatures below average in southern New Zealand.

EXTREMELY SUNNY IN NELSON, LESS SUN THAN NORMAL IN AUCKLAND, THE CENTRAL NORTH ISLAND HIGH COUNTRY AND BAY OF PLENTY

It was extremely sunny in Nelson with a record high total of 878 hours (20 percent above normal). The earliest Nelson and New Zealand sunshine records commenced in 1930. It was also sunnier than usual in Marlborough, Buller, and north Canterbury, with totals at least 10 percent above normal. Record high summer sunshine was recorded at Nelson, the highest in records going back to 1935. Hours of bright sunshine were below average in Auckland, eastern Bay of Plenty, King Country and Tongariro.

EXTREMELY DRY IN CENTRAL NEW ZEALAND

Extremely low summer rainfall occurred throughout Marlborough and Wellington where rainfall was less than 25 and 50 percent of normal respectively. Some areas within these regions experienced their driest summer since that of 1907/08 – almost a century ago. Nelson was also very much drier than average with totals less than 50 percent of normal. Other regions with below average rainfall were Canterbury and Taranaki, with totals between 50 and 75 percent of normal. Near or record low summer rainfall was recorded at

Paraparaumu, 96 mm 45% of normal, 2nd lowest in records back to 1945;

Kelburn, Wellington, 82 mm, 36% of normal, 3rd lowest in records back to 1862 (52 mm 1907/08, 78 mm 1886/87);

Wellington Airport, 71 mm, 37% of normal, lowest on record back to 1960

Wallaceville, 114 mm, 45% of normal, wnd lowest in records back to 1924 (106 mm in 1972/73);

Blenheim, 27 mm, 19% of normal, 2nd lowest in records back to 1902 (18 mm in 1907/08)

Winchmore, 99 mm, 57% of normal, 3rd lowest in records back to 1947).

WET IN EASTERN BAY OF PLENTY

The summer was unsettled in Bay of Plenty (especially in the east), where rainfall ranged from 125 to 185 percent of normal. It was also wetter than usual in eastern areas of Northland, Coromandel, and parts of Waikato, Gisborne and Wairarapa with rainfall about 120 percent of normal. Near or record high summer rainfall was recorded at Whakatane with 382 mm, 147% of normal and 3rd highest in records back to 1975. Rainfall was near average over the remainder of the country.

WARM IN AUCKLAND, WAIKATO, BAY OF PLENTY AND CENTRAL NEW ZEALAND, RATHER COOL IN THE SOUTH OF THE SOUTH ISLAND

Above average temperatures occurred throughout Auckland, Waikato, Bay of Plenty, Wellington, southern Wairarapa, Marlborough and Nelson, all at least 0.5oC above normal.

Below average temperatures occurred in Central Otago, and Fiordland, with mean temperatures at least 0.5oC below normal. Elsewhere temperatures were near normal.

EXTREMES

Temperature

The highest air temperature for summer was 35.3oC, recorded at Timaru Airport on the 4th of February. The highest February air temperature on record for this location is 39.8°C.

The lowest summer air temperature was –2.8oC, recorded at Ranfurly on the 7th of February after a clearance from cold southerly conditions. The lowest February air temperature on record for this location is -3.1°C.

High rainfall – floods

Severe thunderstorms occurred over Rotorua during the early hours of the 8th of December, with spectacular lighting for 3 hours, along with localized heavy rainfall and surface flooding. Rainfall totalling 150 mm was measured on a farm at Lake Rotoiti (in the Rotorua region). A number of Masterton houses, shops and businesses were flooded during heavy rainfall during thunderstorms on the 12th. Nearby, Carterton measured 70 mm.

A north westerly thunderstorm produced 246 mm of rainfall in 24 hours at Mt Cook over the Christmas period.

High rainfall occurred in Coromandel on the 11th February, with totals as high as 120 mm recorded at Whitianga, and at least 50 mm throughout much of eastern Northland, Bay of Plenty, Waikato and Wanganui. Further high rainfall occurred in Bay of Plenty and Gisborne on the 17th February, Whakatane recording 130 mm.

Damaging winds

Northeasterlies up to strong gale force broke windows at an Akaroa property during the late afternoon on 13 December.

Winds of up to 170 kmh from the south, recorded at Taiaroa Head, Otago Harbour, lashed the South Island on 16 January, causing power blackouts, blew fruit off trees in Central Otago and yachts off their moorings. Wellington was also battered by winds up to 140 kmh, lifting roofs and bringing down power lines. A wind gust of 161 kmh was recorded at Puysegur Point, at the southwest tip of the South Island.

Severe fires and drought

Severe grass fires, cited as the worst in the area since European settlement, devastated about 7000 ha of grassland in the Wither Hills/Awatere Valley area near Blenheim from the 26th through 28th December. These occurred during strong, hot and very dry northwesterlies. Temperatures of near 30°C fanned the flames over the tinder dry region. Between 2000 - 4000 sheep and 100 cattle were estimated to have been lost due to the fires.

Severe soil moisture deficits developed in Marlborough in December, and spread to Nelson, Canterbury and Wellington by the end of summer. Very low river flows had developed in the Nelson and Marlborough districts by the end of February.

Severe hailstorms

A sudden and violent hailstorm, lasting about 10 minutes occurred in the Masterton area about 6 pm on 7 January. Hailstones, some the size of golfballs (up to 4 cm in diameter) were reported. On two orchards all the apple and pear crops were lost, with severe damage to fruit in others. Over half the grapes were lost in one orchard. The severe hailstorm also broke windows and skylights, and damaged cars. The overall estimate of losses is $5 million.

Golf ball size hailstones were reported at Alexandra on 8 January, causing significant damage to some cherry crops.

For further information, please contact:

Dr Jim Salinger, NIWA - Auckland,

Tel (09) 375 2053 (Business) or (09) 527 3939 (after hours)

or Stuart Burgess, NIWA - Wellington, (04) 386 0569.

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