NIWA National Climate Summary – January 2001

•{\f "Symbol" \s 10} SEVERE SOIL MOISTURE DEFICITS NOW IN FOUR REGIONS

VERY DRY OVER MUCH OF NEW ZEALAND

•{\f "Symbol" \s 10} COLD, ESPECIALLY IN CANTERBURY, OTAGO AND SOUTHLAND

•{\f "Symbol" \s 10} SUNNY IN TARANAKI AND MANY SOUTH ISLAND AREAS
•{\f "Symbol" \s 10} FREQUENT SOUTHERLY QUARTER WINDS OVER THE COUNTRY

A continuation of severe soil moisture deficits in Marlborough and the development of similar conditions in Nelson, north Canterbury and south of Napier were features of climatic conditions during January. High soil moisture deficits have also developed now throughout Auckland, Waikato, Bay of Plenty, the southern half of the North Island, and from Nelson to Otago.

These conditions reflect the very dry conditions that prevailed in many areas during January, with rainfall less than a quarter of normal in Wellington, Nelson and Marlborough, and half of normal in many other areas. Rainfall was only average in parts of Northland and eastern Otago, and above average in Gisborne.

Overall, January was a cold month, especially in the east of the South Island, with more southerly quarter winds than normal. These winds produced cold snaps on a few occasions, and resulted in mean temperatures about 1°C below normal, with January temperatures in a few areas over 2°C below normal. The national average temperature was 15.9°C. This was 1.2°C below the 1961 – 1990 normal. Temperatures were about 1°C lower than during December 2000. It was very sunny in Taranaki and much of the South Island.

January’s climate patterns were due to more frequent anticyclones (‘highs’) centred south of Hobart, with lower than average pressures southeast of the Chatham Islands. These systems produced much more prevalent cool south to southwest airflows especially over the South Island.

VERY DRY IN WELLINGTON, NELSON AND MARLBOROUGH

Rainfall was very low in Wellington and the north of the South Island with totals less than 25 percent of average. Blenheim’s 3- month rainfall total of 39 mm was the lowest for any November to January period in records going back to 1930. It was also very much drier than average over the remainder of the North Island, except Gisborne and parts of Northland, and in the west and inland areas of the South Island, with rainfall 50 percent (half) or less than normal.

Extremely low January rainfall was recorded at:

Levin 12 mm, 14%, 2nd lowest since 1896

Kelburn, Wellington 13 mm, 16%, 5th lowest since 1862

Wellington Airport 7 mm 10%, Lowest since 1960

Wallaceville 20 mm , 23%, lowest since 1924

Blenheim 2 mm, 6%, lowest since 1930

Blenheim Airport 5 mm, 9%, 3rd lowest since 1941

January’s rainfall was above from Whangarei to Dargaville in Northland and Gisborne, with totals between 130 and 175 percent of Normal.

BELOW AVERAGE TEMPERATURES, ESPECIALLY IN THE EAST OF THE SOUTH ISLAND

It was very much colder than usual in Canterbury, Otago and Southland, with mean temperatures at least 1.5°C below average, making it the coldest January in about 50 years in these regions. Inland areas of Otago were particularly cool, with mean temperatures more than 2.5°C below average. Mean temperatures were 1 to 1.5°C below average in the remainder of the South Island, north Taranaki and Northland. Other regions recorded mean temperatures at least 0.5°C below average.

Extremely low January mean temperatures were recorded at:

Christchurch Airport, 15.2, -2.0°C, 2nd lowest since 1954

Lincoln, 14.9, -1.9°C, lowest since 1930 (records go back to 1862)

Dunedin 13.3, -1.9°C, lowest since 1947 (records began 1853)

Lauder (Central Otago) 13.7, -2.4°C, lowest since 1925

Clyde 15.2, -2.7°C, lowest since 1984

SUNNY IN TARANAKI AND THE MUCH OF THE SOUTH ISLAND

Sunshine and solar radiation totals were 120 percent of normal Taranaki and at least 110 percent of normal in parts of Northland and much of the South Island, except south Canterbury and Otago.

HIGHLIGHTS

Extreme temperatures

The highest air temperature for the month was 32.3oC, recorded at both Napier Airport and Blenheim Airport on the 24th and 23rd respectively. The highest January air temperatures for these locations are 36.9°C (Napier) and 36.3°C (Blenheim). .

The lowest air temperature for the month was –2.3oC, recorded at Ranfurly on the 28th in cold southerly conditions. This is the lowest January temperature at Ranfurly in records back to 1975.

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.

High rainfall

The highest 1-day rainfall was 140 mm recorded at Haast in South Westland.

Damaging winds

Winds of up to 170 kmh, 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.

For further information, please contact:

Dr Jim Salinger, NIWA - Auckland,

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

© Copyright NIWA 2001. All rights reserved.

ENDS

© Scoop Media