Summer 2008-09

Wet in many areas; mild and sunny in the North Island and northern South Island; heat wave in early February.

• Rainfall: Above normal in the north, west and south of the North Island, Marlborough, mid- and south Canterbury and Otago; below normal in Hawke’s Bay and Westport
• Temperature: Above average for most of the North Island and the north of the South Island; below average in mid- and south Canterbury, Otago and coastal Southland.
• Sunshine: Near normal for most of New Zealand; below normal in Otago and Southland

Summer rainfall was above normal (120 – 150% of normal) in parts of Northland, Auckland, Waikato, Manawatu, Wellington and Otago. Some locations in Marlborough and south Canterbury received nearly double their normal summer rainfall totals. Hawke’s Bay and Westport received between 50 and 80 percent of normal summer rainfall. Other areas received near normal rainfall for summer. Severe soil moisture deficits in many eastern areas of the country eased to near normal levels by the end of February.

Summer overall was warmer than average (by between 0.5 and 1.5°C) for most of the North Island and the north of the South Island. A significant heat wave was experienced in many parts of the country from 7 – 12 February, when several record high temperatures were set. Temperatures were below the long-term summer average by between 0.5 and 1.5°C throughout much of inland mid- and south Canterbury, Otago and coastal Southland. The national average temperature of 16.7 °C was 0.1 °C above average for summer.

December and January’s climate was dominated by more ‘highs’ (anticyclones) to the east of the country and more ‘lows’ (depressions) than normal in the Tasman sea, resulting in stronger than normal north-easterly winds over the country. In February, the first two weeks were very warm, associated with frequent warm north-westerly wind flows onto the country, whereas the last two weeks were dominated by more southerly airflows onto the South Island than normal for this time of year, which contributed to the cool temperatures in the south.

Major highlights

• Heavy rain fell in Queenstown and on the West Coast overnight on 2 January. River levels in the Haast and Callery (near Franz Josef) Rivers rose quickly as a result. On 3 January, thunder and hail in Christchurch forced the postponement of the international cricket match against the West Indies, while large, 2 cm hailstones whipped across roads and buildings in Waipara, bringing traffic to a standstill, and denting cars.
• On 20 February, severe rain caused surface flooding in parts of Wellington, Levin, and Palmerston North, and caused raw sewage to overflow into central Wellington, the harbour, and Lyall Bay. In Tauranga, the severe rain caused the postponement of the Kapa Haka festival, the first time this had happened in 36 years. In South Canterbury and north Otago, surface flooding affected SH1 and SH8, and closed some minor roads.
• Several locations experienced record or near-record high summer maximum and minimum temperatures in the six day “heat wave” from the 7^th to the 12^th of February. The highest temperature during summer 2008/09 was 38.0°C recorded at Culverden on the 8^th of February (the highest summer maximum temperature for this location). The minimum temperature of 22.5°C at Tauranga airport on the night of the 10^th/11^thof February was the highest minimum for the country for summer (and the highest summer minimum temperature at that location since records began in 1941).
• The lowest temperature during summer was recorded at Hanmer Forest on 6 December where the minimum temperature was -1.7°C (not a summer record for this location). A cold southerly air flow persisted for three days from 11 – 14 February resulting in minimum temperatures of -1.0°C at Ranfurly, ‑0.6°C at Manapouri, 1.7°C at Queenstown and 1.9°C at Dunedin airport.
• Of the six main centres, Tauranga was the warmest and sunniest, Wellington the wettest, and Christchurch was the driest.

Full report

• Summer 2008-09 climate summary (PDF 84 KB)

For further information, please contact:

Dr Andrew Tait – Climate Scientist NIWA National Climate Centre – Wellington Phone +64 4 386 0562 [email protected]

Dr James Renwick – Principal Scientist NIWA National Climate Centre – Wellington Phone +64 4 386 0343 [email protected]

Michele Hollis – NIWA Communications Manager Phone +64 4 386 0483 [email protected]

Acknowledgement of NIWA as the source is required.