December 2004

Temperature: Coldest December since 1945, many new records set

Rainfall: Well above average in the east from Hawke’s Bay to Southland; below average rainfall in Westland and Fiordland

Sunshine: Rather cloudy in many areas

December was the fifth coldest on record overall since reliable temperature measurements were established in 1853, and the coldest since 1945. The national average of 13.4°C was 2.2°C below normal, lower only in 1902 (12.9° C), 1911 (13.0 °C), 1914 (13.2°C), and 1945 (13.3°C). The December 2004 temperatures were equivalent to mid spring temperatures, rather than those of an early summer month. Record-breaking low mean December temperatures occurred in many places, being up to 4°C below average in inland parts of Canterbury, Otago, and Southland. The cold weather slowed the growth and ripening of berries, stone fruit, and many horticultural crops. Along with the cold temperatures, frequent southerlies produced a very wet month, with more than 200 percent (twice) of average rainfall in some eastern regions from Hawke’s Bay to Southland. However, the same conditions produced less than 75 percent (three quarters) of average rainfall in sheltered parts of south Westland and Fiordland. Soil moisture deficits persisted in Gisborne, coastal Marlborough, and Central Otago. Sunshine hours were well below average in the north and west of the North Island, and the southeast of the South Island. There were many more depressions ('lows') than average, often centred south of the Chatham Islands (where surface pressures (where at least 12 hPa below average). These produced the strongest south to southwest airflow over New Zealand on record.

Highlights

  • The highest December 2004 temperature was 31.0°C, recorded at Napier Airport on the 2nd. The lowest temperature for the month was -3.7°C, recorded at Wreys Bush (Southland) on the 20th.
  • Ground frost occurred on the 12th of December in inland sheltered areas of the North Island, and on several days during the month in many locations in the South Island.
  • A very cold and unseasonable southerly outbreak brought gale force southerlies to exposed southern and eastern areas over the weekend of 18-19 December, with hail in Auckland, and the beach at Port Waikato during thunderstorms on the 19th. Hailstones ruined fruit in parts of Auckland, Hawke’s Bay, Tasman, and Canterbury. Damaging winds occurred in Auckland. Snowfall occurred as low as 600 m in the South Island, with a light fall on the Desert Road in the central North Island . Skiing was still possible on Mt. Ruapehu over the Christmas period.
  • Damaging winds associated with a small tornado occurred in Auckland on the 22nd.
  • Rainfall totalled at least 60 mm occurred in the Bay of Islands on the 29th and Bay of Plenty on the 30th. The 28-29th was also very wet in Buller and Westland, with 162 mm in Takaka on the 29th and 280 mm for the 2-day period recorded at Franz Josef.
  • Of the four main centres Wellington was the sunniest and Christchurch the driest. Rainfall was above average and temperatures were well below average in all four cities. Sunshine hours were near average in Wellington, and below average in Auckland, Christchurch and Dunedin.

Temperature

North Island mean temperatures were about 2.0°C below average, and South Island mean temperatures mostly 2.0 to 4.0°C below average, the largest anomalies being in the east.

Rainfall

Rainfall was well above average in eastern regions from Hawke’s Bay to Southland, some locations recorded more than 200 percent (twice) of average. Rainfall was also above average in parts of Northland, Auckland, Coromandel, Waikato, Wanganui, Ruapehu, Manawatu, Horowhenua, Wellington, and Nelson. In contrast, December rainfall totals were less than 75 percent (three quarters) of average, in parts of south Westland and Fiordland. Rainfall was near average elsewhere.

Sunshine

Sunshine hours were well below average in parts of Northland, Auckland, Waikato, King Country, Manawatu, Otago, and Southland. However, they were near average elsewhere.

Full report

Full details of December 2004 summary.

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.