Winter 2015

A winter with many extreme weather events.

Overview

Overall, winter temperatures were near average (-0.50°C to +0.50°C) across most of the country. There were pockets of below average temperatures (-1.20°C to -0.51°C) in western Waikato, Tararua, Wairarapa, mid-Canterbury, Tasman and coastal Otago. Pockets of above average temperatures (+0.51°C to +1.20°C) were also present in Christchurch, central Otago and the Manawatu. The nation-wide average temperature in winter 2015 was 8.4°C (equal to the 1981-2010 winter average, using NIWA’s seven-station temperature series which begins in 1909)^[1]. However, this average picture of winter temperatures does not convey the nature of the extremely low temperatures that affected the Mackenzie Country and Central Otago in late June. These temperatures were some of the lowest ever recorded in New Zealand and will make winter 2015 one to remember. See the Highlights and Extreme Events section for more details on this event.

Pressures were higher than normal over the North Island and lower than normal to the south of New Zealand. This resulted in a westerly to southwesterly flow anomaly for the winter season which was subsequently reflected in the seasonal rainfall anomalies across the country. Specifically, rainfall was below normal (50-79%) or well below normal (< 50%) in eastern parts of both Islands, including Northland, Bay of Plenty, Gisborne, Hawke’s Bay, Wairarapa and north Canterbury. In contrast, rainfall was plentiful for many western areas of New Zealand. Rainfall was either above normal (120-149% of winter normal) or well above normal (> 149% of the winter normal) for southwestern and western parts of both the North and South Islands as well as coastal Otago. Rainfall was typically near normal (80-119% of the winter normal) for remaining areas of the country. As of 1 September 2015, soil moisture levels were below normal for this time of year for Hawke’s Bay, coastal Wairarapa, eastern parts of Canterbury and North Otago. 

Winter sunshine was near normal for most of the country (90-109%). Above normal (110-125%) sunshine was observed in western Waikato and Marlborough, and below normal sunshine (75-89%) was observed in Taranaki.

Winter 2015 saw numerous major snowfall events that closed highways across the South Island and parts of the North Island, as well as causing power outages. The Highlights and Extreme Events section has more information on these snowfall events.

Further Highlights:

• The highest temperature was 23.8°C, observed at Christchurch (Riccarton) on 3 August.
• The lowest temperature was -21.0°C, observed at Tara Hills on 24 June.
• The highest 1-day rainfall was 466 mm, recorded at North Egmont 19 June.
• The highest wind gust was 189km/hr, observed at Cape Turnagain on 29 June.
• Of the six main centres in winter 2015, Auckland was the warmest and wettest, Dunedin was the cloudiest, Christchurch was the coolest and driest and Hamilton was the sunniest.
• Of the available, regularly reporting sunshine observation sites, the sunniest four stations so far in 2015 (1 January to 31 August) are: Blenheim (1742 hours), Whakatane (1724 hours), Appleby (1701 hours) and Waipara West (1671 hours).

Download the full report:

Seasonal Climate Summary - Winter 2015 [ PDF 693.13 KB]

For further information, please contact:

Mr Chris Brandolino NIWA Forecaster – NIWA National Climate Centre Tel. (09) 375 6335, Mobile (027) 866 0014