National Climate Summary – November 2011: Extremely dry north of Taupo; wet over South Island

• Rainfall: Extremely dry in Northland, Firth of Thames, Eastern Waikato, Coromandel, Western Bay of Plenty, and Taupo. Wet around Palmerston North, and very wet over much of South Island, especially Otago, South Canterbury, and the Lakes District.
• Soil moisture levels: Significant deficit north of Taupo, as well as Gisborne, Hawkes Bay, Marlborough, and central Otago.
• Temperatures: Above average in the northeastern North Island. Near average elsewhere, except below average along the south and west coastline of the South Island.
• Sunshine: A sunny month in the east, but normal or below normal sunshine elsewhere.

Much stronger than normal southwest winds affected New Zealand during November 2011, squeezed between higher than normal pressures over the Tasman Sea and lower pressures to the southeast of the country. The southwesterly winds produced a cooler than usual month along the southern and western coastline of the South Island, but a warmer than average month in the sheltered northeast coast of the North Island. These winds also produced an extremely dry month for regions north of Taupo, but in contrast it was an unsettled and very wet month across much of the South Island.

It was an extremely dry month in Northland, Firth of Thames, eastern Waikato, Coromandel, Western Bay of Plenty, and Taupo, with less than half of normal November rainfall observed. Whangarei received only 10 mm of rainfall during the month (it was the second-driest November there, in records which begin in 1937) and Tauranga reported only 13 mm (also the second-driest November there, in records which begin in 1898). Elsewhere in the North Island, rainfall totals in November were generally below normal, with the notable exception of around Palmerston North (well above normal rainfall) and Wellington (near normal totals). In contrast, rainfall exceeded 200 percent of normal in parts of central Otago, South Canterbury and the Lakes District. Elsewhere over the South Island, rainfall was generally normal or above normal (between 100 and 149 percent of normal), with the exception of Marlborough, which experienced below normal rainfall. Significant soil moisture deficit (more t
han 110 mm of deficit) was observed in regions north of Taupo, also Hawkes Bay, Gisborne, Marlborough, and central Otago, at the end of November.

Mean temperatures in November were above average (between 0.5°C and 1.2°C above November average) across much of the northeast North Island. Across most of the remainder of the country, temperatures were close to average (within 0.5°C of November average). The only exceptions were seen along the southern and western coastline of the South Island, where temperatures were below average (between 0.5°C and 1.2°C below average). The nation-wide average temperature in November was 13.5°C (0.2°C below the 1971–2000 November average), using NIWA’s seven-station temperature series which begins in 1909.

November 2011 was a sunny month in eastern regions of both islands (from Coromandel down to Hawkes Bay, as well as the eastern South Island), consistent with the frequent southwest winds during the month. In contrast, below normal sunshine totals were observed around Palmerston North and around Hokitika (with totals between 75 and 90 percent of November normal). Elsewhere, sunshine totals were near normal.

Further Highlights:
• The highest temperature was 29.5°C, observed at Middlemarch on 27 November.
• The lowest temperature was -6.4°C, at Mt Cook on 5 November (2nd lowest for November).
• The highest 1-day rainfall experienced was 161 mm at Arthurs Pass on 20 November.
• The highest gust recorded was 156 km/hr at Akitio (Wairarapa) on 25 November.
• Of the six main centres in November 2011, Tauranga was the warmest, driest and sunniest, Wellington the wettest, and Dunedin the coolest.

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