Cloudy, warm, and extremely wet

National Climate Summary – August 2010: Cloudy, warm, and extremely wet

• Rainfall: Extremely wet for most North Island regions, as well as the north and east of the South Island. Double normal August rainfall for Kaitaia, Coromandel, Bay of Plenty and eastern Otago. • Sunshine: Very cloudy for the North Island, as well as inland and eastern South Island. • Temperatures: Above average for all regions, except eastern Otago.

August 2010 was characterised by lower pressures than normal over the Tasman Sea and New Zealand, resulting in a much wetter and cloudier August than normal. Frequent northerly air streams affected the North Island during the month, with more easterly winds over the South Island.

It was an extremely wet August across most of the country. Rainfalls were well above normal (more than 150 percent of normal) for all of the North Island except Hawkes Bay, as well as in Nelson and Marlborough, and parts of Canterbury and Otago. Double normal August rainfall was observed around Kaitaia, Coromandel and the Bay of Plenty, and eastern Otago. It was the wettest August on record for parts of the Bay of Plenty, Wanganui and Turangi. In contrast, Fiordland and Southland recorded below normal rainfall (between 50 and 80 percent of normal). For Hawkes Bay and the West Coast, rainfall was near normal (between 80 and 120 percent of normal).

It was a very cloudy month over much of New Zealand. August sunshine totals were below average (between 75 and 90 percent of normal) across the entire North Island, as well as for inland and eastern areas of the South Island. Turangi, Stratford, Martinborough and Christchurch recorded well below average sunshine (between 50 and 75 percent of normal). It was the cloudiest August on record for Turangi and Martinborough. Sunshine hour totals were closer to normal in the west and south of the South Island (ranging between 90 and 110 percent of normal).

August 2010 mean temperatures were above average (between 0.5°C and 1.2°C above average) across all regions of New Zealand, except for eastern Otago, where temperatures were near average (within 0.5°C of average). Small areas of well above average temperatures (more than 1.2°C above average) were observed in Northland, eastern Bay of Plenty, Nelson and Fiordland. The New Zealand national average temperature was 9.6°C (0.9°C above the 1971-2000 August average).

Further Highlights: • The highest temperature was 21.9°C, recorded at Motueka on the 15th (a new August record). • The lowest temperature was -12.6°C, recorded at Lake Tekapo on the 10th (2nd-lowest August temperature on record there). • The highest 1-day rainfall was 255 mm recorded at North Egmont on the 13th (not a record). • The highest wind gust was 130 km/hr, recorded at Stephens Island on the 1st (not a record). • Of the six main centres, Auckland was the warmest, Christchurch and Dunedin equally the coolest, Tauranga the wettest but also the sunniest, and Dunedin the driest.

ENDS