October: Wet and cloudy for many regions; easterlies prevail

National Climate Summary – October 2011: Wet and cloudy for many regions; easterlies prevail

• Rainfall: Very wet in the north and west of the North Island, and the north and east of the South Island. Very dry in Gisborne. Below normal rainfall in the Wairarapa, and across the west and south of the South Island.
• Temperatures: Above average on the West Coast, and northern half of the North Island. Below average for the eastern South Island. Near average elsewhere.
• Sunshine: Extremely cloudy from Taranaki to Wellington, Marlborough and Canterbury, and cloudier than normal in most other regions. Sunny for Invercargill and Balclutha.
• Soil moisture: Drier than usual for the eastern North Island. Wetter than usual in the north and east of the South Island.

October 2011 was characterised by periods of northeasterly winds over New Zealand. Higher pressures than normal were observed south of the country, with lower pressures than normal over the north Tasman Sea. The easterly events produced a wet and cloudy month for many regions, and a cooler October for the east coast of the South Island. In comparison, it was unusually warm, sunny and dry along the West Coast.

October 2011 rainfall totals were above normal or well above normal (exceeding 120 percent of October normal) across much of the north and west of the North Island, as well as the north and east of the South Island. Rainfall totals were extremely high (with totals exceeding 200 percent of normal) in parts of: Bay of Plenty, Nelson, Canterbury, the Lakes District and Central Otago. In marked contrast, it was a very dry month in Gisborne (with less than 50 percent of normal rainfall), and it was drier than normal in parts of the Wairarapa and across the west and south of the South Island (with totals less than 80 percent of normal). Soils remain drier than usual for the time of year in the eastern North Island, but are wetter than usual in the north and east of the South Island.

October 2011 was rather cloudy, with many regions of the country experiencing below normal sunshine hours (between 75 and 90 percent of October normal). In particular, Taranaki to Wellington, Marlborough and Canterbury experienced extremely low sunshine totals (generally less than 75 percent of normal). It was the cloudiest October on record for the Hutt Valley, and Christchurch, since records began at those sites in the 1930s. In contrast, it was sunnier than normal for Invercargill and Balclutha. Across the southwest of the South Island, including along the West Coast of the South Island, as well as in Northland, Auckland, and parts of the Bay of Plenty, sunshine hours were close to normal.

Mean temperatures in October were above average (between 0.5°C and 1.2°C above October average) across much of the northern North Island, as well as along the West Coast. In contrast, temperatures were below average (between 0.5°C and 1.2°C below average) for much of the eastern South Island. Elsewhere, temperatures were close to average (within 0.5°C of October average). The average temperature in October 2011 was 12.4°C (0.3°C above the 1971–2000 October average) using NIWA’s seven-station temperature series which begins in 1909.

Further Highlights:
• The highest temperature was 26.8°C, observed at Motueka on 21 October (2nd highest for October at this site).
• The lowest temperature was -5.0°C, at Tara Hills on 9 October (4th lowest for October at this site).
• The highest 1-day rainfall experienced was 166 mm at North Egmont on 3 October.
• The highest gust recorded was 183 km/hr at Southwest Cape, Stewart Island, on 24 October.
• Of the six main centres in October 2011, Auckland was the warmest, Tauranga the sunniest, Hamilton the wettest, and Dunedin the driest and coolest.

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