September 2005

  • Rainfall: Below average in many regions, especially Nelson
  • Temperature: Above average almost everywhere
  • Sunshine: Sunny over much of the North Island, below average sunshine in coastal Canterbury
  • Snowstorm: Significant snowfall event affects the eastern South Island

September was the third consecutive month with above average temperatures. September was also drier and sunnier than normal in many regions, especially during the first two weeks and in the closing days. However, a significant very cold outbreak with snow to low levels followed by severe frost affected some areas during the third week. Rainfall was well below average in parts of Nelson. Appleby’s rainfall totalled 9 mm (11 percent of normal), was the lowest September total in more than 70 years of measurement. Rainfall was less than 50 percent (half) of normal in Gisborne and Marlborough. A lack of substantial rainfall in North and Central Otago and South Canterbury (less than 25 mm for the month in some areas) resulted in a continuation of significant soil moisture deficits. Fire bans existed in parts of Canterbury and Otago at the start of the month. September was the third consecutive month with above average temperatures. The month was warmer than average almost everywhere, the national average temperature of 11.1 °C being 0.7 °C above normal. September was sunnier than average in many North Island regions south of Waikato and Bay of Plenty, inland south Canterbury and Southland. There were more anticyclones than average east of the North Island, and also south of the South Island. This pattern produced more frequent northerlies over the North Island.

Other Highlights

  • The highest temperature during September 2005 was 23.6 °C recorded at Hanmer Forest on the 11th, and in Henderson, Auckland on the 12th. The lowest temperature for the month was -7.0°C, at Arthurs Pass, on the 20th.
  • The highest wind gust for the month was 156 km/h from the southwest, recorded at Cape Reinga on the 19th.
  • High rainfall totalling 338 mm was recorded at Arthur’s Pass between 4 and 7 September.
  • A tornado struck Hokitika on the 5th, lifting a house roof, smashing windows, overturning a furniture truck, and leaving a trail of damage.
  • A deep depression was accompanied by high rainfall and gale force winds in parts of Northland, Bay of Plenty and Taranaki on the 18th, with a damaging tornado in Hamilton. An unseasonably cold southerly outbreak followed, with snowfall to sea level in Canterbury on the 19th. The southerlies produced hail showers in the lower North Island, and resulted in significant fresh snowfall in the central North Island mountains, and closed the Desert Road. Severe ground frosts followed in some areas over 20-21 September. Frost prevention measures occurred in many areas, including the use of helicopters, to avoid potential plant damage.
  • Of the four main centres Christchurch was the driest and Wellington was the sunniest. Auckland was warmer than average. Wellington was warmer, sunnier, and much drier than average. Christchurch was rather cloudy and drier than average. Dunedin was sunnier with near average rainfall and temperature.

Rainfall

Rainfall was less than 25 percent of normal rainfall in parts of Nelson, and less than 50 percent of normal in Gisborne and Marlborough. Totals were average or below average in most other regions. Scattered areas of above average rainfall (at least 125 percent of normal) occurred in isolated parts of Northland, Waikato, Wanganui, Manawatu, and Westland.

Temperature

Mean temperatures were above average almost everywhere, and almost 1.5 °C above average in parts of Otago, and 1.0 °C above average in the northern half of the North Island from Northland to Bay of Plenty, as well as Wellington, and much of the South Island.

Sunshine

Sunshine hours were at least 120 percent of average in Manawatu and Gisborne, and more than 110 percent of average in many North Island regions south of Waikato and Bay of Plenty, inland south Canterbury and Southland. In contrast, it was rather cloudy in coastal areas of Canterbury.

Full report

Full details of September 2005 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.