National Climate Summary: The Big Dry Continues
National Climate Summary – March 2001
The Big Dry Continues
* VIRTUALLY NO RAIN IN THE NORTH AND EAST OF THE
SOUTH ISLAND, BELOW AVERAGE RAINFALL ALMOST EVERYWHERE
* VERY SUNNY IN THE SOUTH ISLAND AND LOWER NORTH ISLAND
* COOL IN THE EAST OF THE NORTH ISLAND, WARM OVER MUCH OF THE SOUTH ISLAND
Virtually no March rainfall occurred in many areas of the South Island from Golden Bay across to Nelson, and Marlborough to Southland. Many sites in Canterbury and Otago measured totals of 5 mm or less. As a result severe soil moisture deficits continued in Marlborough, Nelson, Canterbury and Wellington, combined with very high to extreme fire risk. The lack of rainfall has extended the severe soil moisture deficits in the north and east of the South Island from Nelson to Otago, and these have spread to central Hawke’s Bay in the North Island. Rainfall totaling more than 300 mm in the Southern Alps from 26-28 March recharged alpine rivers only, to bring some relief to parched east coast areas downstream. Rivers further east remained at record low levels, with some completely dry.
Near or record low rainfall was measured in many areas from Golden Bay across to Nelson, and from Marlborough to inland Southland, with totals much less than 25 percent (a quarter) of normal at most locations. Rainfall was also extremely low in Auckland, and parts of western Northland, with rainfall 25 percent (a quarter) or less of normal. Waikato, eastern Bay of Plenty, Gisborne, central Wairarapa, southern Buller, southern Buller, Westland and the Southern Alps received near normal rainfall. For the year to date, the Wellington January – March total of 61 mm is the lowest since records began in 1862, and the Blenheim 3-month total of 20 mm the 2nd lowest in records going back to 1902.
It was very sunny over much of the South Island and lower North Island, with extremely high sunshine hours in Nelson, Wellington and Invercargill. However, sunshine totals were well below average in Gisborne. March temperatures were near or above normal over much of the South Island, and near or below normal over much of the North Island. The national average temperature was 16.0°C, which was 0.1°C below the 1961-1990 normal.
March’s climate patterns were due to very persistent anticyclones (‘blocking highs’) centred over and to the east of New Zealand, bringing dry, settled conditions to most areas throughout much of the month. Lower than average pressures prevailed in the northwest Tasman Sea, and brought more prevalent easterlies over northern New Zealand.
INCREDIBLY DRY IN THE NORTH AND EAST OF THE SOUTH ISLAND
Rainfall was extremely low in many areas throughout the north and east of the South Island, from Golden Bay across to Nelson, and from Marlborough to inland Southland, with totals much less than 25 percent of normal at most locations. Many Canterbury and Otago sites measured rainfall or 5 mm or less. Rainfall was also extremely low in Auckland, and parts of western Northland, with rainfall 25 percent of normal or less. Other rather dry regions, with less than 50 percent of normal rainfall, were Coromandel, western Bay of Plenty, and most North Island areas south of a line from New Plymouth to Napier.
Rainfall was near average in Waikato, eastern Bay of Plenty, Gisborne, central Wairarapa, southern Buller, Westland, and the Southern Alps.
Near or record low March rainfall was recorded at:
of normal Year
Records began Comments
Dargaville 17 19 1943 Equal lowest
Auckland, Henderson 21 16 1986 Lowest
Auckland, Owairaka 13 13 1949 Lowest
Auckland Airport 20 24 1963 2nd lowest
Wellington Airport 15 20 1960 3rd lowest
Waiouru 22 27 1961 2nd lowest
Motueka, Riwaka 7 7 1943 4th
Nelson Airport 14 17 1941 4th lowest
Blenheim Research 12 24 1986 Lowest
Blenheim Airport 8 13 1941 3rd lowest
Winchmore 4 7 1947 Equal lowest
Christchurch Airport 11 20 1944 3rd equal lowest
Lincoln 4 7 1881 Lowest
Akaroa, Rue Lavaud 3 3 1978 Lowest
Timaru Airport 4 8 1957 Lowest
Tara Hills 1 3 1950 Lowest
Dunedin Airport 8 12 1963 Equal lowest
Dunedin, Musselburgh 2 3 1918 Lowest
Lauder 4 6 1943 3rd Lowest
Clyde 10 23 1983 Equal lowest
Ettrick 8 13 1985 Lowest
Gore 18 22 1943 2nd lowest
Chatham Islands 28 40 1951 4th lowest
VERY SUNNY IN THE SOUTH ISLAND AND LOWER NORTH ISLAND
Sunshine and solar radiation totals were at least 120 percent of normal throughout much of the South Island, and at least 110 percent of normal in the north, west and south of the North Island. Sunshine totals were well below average in Gisborne, with totals less than 80 percent of normal. Near normal sunshine occurred elsewhere.
Near record March sunshine was recorded at:
of normal Year
Records began Comments
Wellington, Kelburn 248 134 1928 Highest
Nelson Airport 279 137 1949 Highest
Invercargill Airport 178 135 1932 2nd highest
COOLER IN THE EAST OF THE NORTH ISLAND, SLIGHTLY WARMER IN MANY SOUTH ISLAND REGIONS
Mean temperatures were near or above normal over much of the South Island, and near or below normal over much of the North Island. Temperatures were 0.5 to 1.0°C above average in Buller, Nelson, Canterbury and Otago, and 0.5 to 1.0°C below average in parts of Northland, eastern Bay of Plenty, Gisborne, and Hawke’s Bay.
* The highest air temperature for the month was 31.1oC, recorded in Christchurch Gardens on the 25th. The highest March air temperature on record for this location is 34.4°C.
* The lowest air temperature for the month was –2.6oC, recorded at Windsor, Otago on the 31st; the lowest March air temperature in this area since at least 1975.
* A tornado, with severe winds, ripped through part of Greymouth at about 4am 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 powerlines 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.
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Acknowledgement of NIWA as the source is required.