National Climate Summary – September 2006

NATIONAL CLIMATE CENTRE SUNDAY 1 OCTOBER 2006

National Climate Summary – September 2006: Extremely dry in the east; third equal warmest on record

- Rainfall: Extremely low in the east from Wairarapa to Otago; above average in Fiordland and coastal Southland

- Significant soil moisture deficits in Central Otago, deficits developing in other eastern regions

- Temperature: Above average, especially in the east from Marlborough to Central Otago

- Sunshine: Very sunny in Gisborne, Otago, and inland South Canterbury

- Very windy in the south of the South Island

September was a month of climate extremes with record low rainfall and high mean temperatures at many locations. Rainfall was low throughout much of New Zealand, especially in the east from Wairarapa to Canterbury, some Canterbury locations recording 10 percent (one tenth) or less of normal rainfall. There was no measurable rainfall at Kaikoura, and about 10 mm or less in some parts of Marlborough, Canterbury and Otago. The low rainfall has resulted in the development of significant soil moisture deficits (110 mm or more) in Central Otago. Soil moisture deficits, although not major, also exist as far north as Marlborough. It was the third equal warmest September on record, with the national average temperature being 11.5 °C, 1.1 °C above normal. Temperatures were above average throughout New Zealand, especially in the east from Marlborough to Otago where they were about 2.0 °C above average producing new records of mean temperature. Maximum temperatures exceeded 20 °C in many eastern regions from 21 through 26 September. Sunshine hours were above normal over much of New Zealand, especially in eastern regions. In contrast, in was unsettled and much windier than normal in Fiordland and along the Southland coast, the only districts where September rainfall was above normal. More anticyclones (‘highs’) predominated over the Tasman and across the North Island, with below average pressures well south of New Zealand. This pattern produced much stronger westerlies than normal over the South Island, and more frequent strong winds than average in Wellington, South Canterbury, Otago, and Southland.

Other Highlights:

- The highest temperature during September 2006 was 25.0 °C recorded in Napier on the 22nd. Near or record high September air temperatures were recorded in Dunedin Airport (24.9 °C), Invercargill (23.1°C) and Queenstown (24.3 °C) on the 25th, and at Gisborne (24.9 °C) on the 26th.

- The lowest air temperature for the month was -5.6 °C recorded at Hanmer Forest on the 11th.

- A wind gust of 180 km/h from the northwest was recorded at Southwest Cape (Stewart Island) on the 2nd, a new record for a wind gust at that site (measurements commenced in 1992).

- High rainfall affected the southwest of the South Island over the 1st, 4th-5th, 15th, 18th-21st, 23rd, and 25th of September. Heavy rainfall totalling 294 mm was measured at Milford Sound from the 18th-21st.

- High rainfall also affected the North of the North Island on the 9th and 10th.

- Christchurch was the driest, Dunedin the sunniest, and Auckland the wettest of the main centres. Rainfall was below normal, and temperatures above normal in all five main centres. It was extremely warm and dry for the time of year in Christchurch. Sunshine hours were near normal in Wellington, and above normal in the four other main centres, with record values in Dunedin.

Rainfall: September rainfall was extremely low, being 10 percent (one tenth) or less of normal in parts of Canterbury, and 25 percent (quarter) or less of normal in Waikato, Southern Wairarapa, Marlborough, and North and East Otago. There was no recordable rainfall at Kaikoura, the first time since records began in 1949. In many of these locations it was the lowest September rainfall on record. Rainfall was also well below normal in many other parts of the North Island, as well as Nelson. In contrast, Fiordland and the Southland coast were the only districts where rainfall was above normal, by as much as 50 percent.

Temperature: Mean temperatures were about 2.0 °C above average in parts of Marlborough, Canterbury, and Otago, and more than 1.0 °C above average in parts of Wairarapa, Hawke’s Bay, Kapiti, Wellington, Nelson, and Southland. Temperatures were also above average in most other regions.

Sunshine: Sunshine hours and/or solar radiation were at least 120 percent of normal in Gisborne, inland South Canterbury, and Otago. It was also sunny in Northland, Auckland, Waikato, Bay of Plenty, Napier, Marlborough, Nelson, and North Canterbury.

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LOW RAINFALL, ESPECIALLY IN THE EAST FROM WAIRARAPA TO CANTERBURY
ABOVE AVERAGE RAINFALL IN FIORDLAND AND THE SOUTHLAND COAST

September rainfall totals were extremely low, being 10 percent (one tenth) or less of normal in parts of Canterbury, and 25 percent (quarter) or less of normal in Waikato, Southern Wairarapa, Marlborough, and North and East Otago. Rainfall was also low with totals 50 percent (half) or less of normal in parts of Northland, Auckland, Thames, much of the west of the North Island from Taranaki to Wellington, as well as Nelson, and 75 percent (three quarters) or less of normal in most other North Island regions, as well as Buller. New low monthly rainfall records occurred in parts of Northland, Waikato, Bay of Plenty, Wairarapa, Marlborough, and Canterbury, and about 10 mm or less was recorded in some parts of coastal Marlborough, Canterbury and Otago. In contrast, Fiordland and the Southland coast were the only districts where rainfall was above (up to 150% of) normal.

Low September rainfall was recorded at:
Location September Rainfall (mm) Percentage of normal Year Records began Comments
Kerikeri EWS 43 24 1982 Lowest
Kerikeri Airport 47 29 1978 Lowest
Kaikohe 61 45 1973 3rd Lowest
Matamata, Hinuera 34 27 1999 Lowest
Te Puke 53 39 1973 Lowest
Rotorua Airport 41 35 1964 2nd lowest
Taupo Airport 24 29 1976 2nd lowest
Pukekohe 42 36 1970 Lowest
Hamilton, Ruakura 21 20 1906 Lowest
Hamilton Airport 28 26 1935 Lowest
East Taratahi 17 25 1972 2nd lowest
Wellington Airport 25 31 1960 3rd lowest
Waiuoru MWD 32 36 1950 2nd lowest
Motueka, Riwaka 23 20 1943 Equal 2nd lowest
Nelson Airport 21 30 1941 Equal 3rd lowest
Nelson, Appleby 11 15 1932 2nd lowest
Blenheim Research 7 14 1929 3rd lowest
Blenheim Airport 10 15 1941 Equal 2nd lowest
Kaikoura 0 0 1949 Lowest
Winchmore 11 21 1947 Equal 3rd lowest
Rangiora 11 19 1999 2nd lowest
Darfield 9 15 1920 Equal lowest
Christchurch Airport 4 8 1944 2nd lowest
Lincoln, Broadfield 3 7 1881 Equal 2nd lowest
Le Bons Bay 10 16 1987 Lowest
Ranfurly 5 19 2000 Lowest
Ettrick 10 22 1985 3rd lowest
Chatham Islands 17 24 1951 Lowest

TEMPERATURE: ABOVE AVERAGE, ESPECIALLY IN THE EAST FROM MARLBOROUGH TO CENTRAL OTAGO

It was the third equal warmest September on record, with the national average temperature being 11.5 °C, 1.1 °C above normal. The only warmer September months were in 1988 (11.9) and 1996 (11.6), with 1969 (11.5) being as warm. Mean temperatures were about 2.0 °C above average in parts of Marlborough, Canterbury, and Otago, producing new record September mean temperatures at several sites in these regions. Mean temperatures were more than 1.0 °C above average in parts of Wairarapa, Hawke’s Bay, Kapiti, Wellington, Nelson, and Southland. They were more than 0.5 °C above average in most other regions.

High September mean temperatures were recorded at:
Location September Mean air temperature (°C) Departure from normal (°C) Year Records began Comments
Mt Ruapehu, Chateau 6.3 +1.6 1981 2nd equalchighest
Ngawi, Palliser 13.9 +2.0 1972 Equal highest
Mahia AWS 13.1 +1.8 1991 Highest
Napier Airport 12.7 +1.3 1974 Equal 3rd highest
Paraparaumu Airport 12.3 +1.4 1953 Equal highest
Wellington Airport 12.7 +1.4 1962 3rd equal highest
Wallaceville 11.8 +1.6 1940 3rd highest
Farewell Spit 12.8 +1.3 1971 Equal highest
Reefton 10.7 +1.4 1960 Equal 3rd highest
Nelson Airport 11.9 +1.7 1943 Highest
Blenheim Research 12.5 +1.8 1932 3rd highest
Blenheim Airport 11.7 +1.4 1941 2nd highest
Kaikoura 11.9 +1.8 1964 Well above normal
Mt Cook Village 8.7 +2.1 1930 2nd highest
Winchmore 10.9 +2.0 1950 2nd highest
Rangiora 10.8 +1.5 1999 Highest
Darfield 11.7 +2.2 1939 Equal 2nd highest
Lincoln, Broadfield 11.2 +1.9 1881 Well above normal
Le Bons Bay 10.9 +2.0 1984 Highest
Lake Tekapo 8.6 +2.1 1927 Well above normal
Timaru Airport 9.9 +1.4 1962 Equal 3rd highest
Tara Hills 9.3 +2.1 1950 Equal highest
Wanaka Airport 9.9 +1.6 1992 Highest
Dunedin Airport 10.5 +1.9 1963 Highest
Dunedin, Musselburgh 11.3 +2.0 1947 Highest
Queenstown 10.3 +1.7 1871 Equal 2nd highest
Lumsden 9.6 +1.7 1982 2nd highest
Clyde EWS 10.4 +1.8 1983 Equal highest
Invercargill Airport 9.7 +1.4 1948 3rd highest

VERY SUNNY IN GISBORNE, OTAGO, AND INLAND SOUTH CANTERBURY

Sunshine hours and/or solar radiation were at least 120 percent of normal in Gisborne, inland South Canterbury, and Otago, and at least 110 percent of normal in Northland, Auckland, Waikato, Bay of Plenty, Napier, Marlborough, Nelson, and North Canterbury. Sunshine hours were near normal in most other regions.

Well above average September sunshine hours were recorded at:
Location September Sunshine (hours) Percentage of normal Year records began Comments
Gisborne Airport 224 130 1905 Well above normal
Lake Tekapo 246 140 1928 3rd highest
Dunedin, Musselburgh 194 150 1932 Equal highest

SEPTEMBER’S CLIMATE IN THE FIVE MAIN CENTRES

Christchurch was the driest, Dunedin the sunniest, and Auckland the wettest of the main centres. Rainfall was below normal, and temperatures above normal in all five main centres. It was extremely warm and dry for the time of year in Christchurch. Sunshine hours were near normal in Wellington, and above normal in the four other main centres, with record high hours in Dunedin.
Location Sept. Mean Temp. (°C) Dep. from normal (°C) Sept. rainfall (mm) % of Normal Sept. Sunshine (hours) % of Normal
Auckland 13.7 +0.8 Above normal 58a 50 Well below normal 181 121 Above normal
Hamilton 12.1 +0.7 Above normal 21 20 Well below normal 176 118 Above normal
Wellington 11.2 +0.6 Above normal 39 38 Well below normal 157 100 Near normal
Christchurch 10.6 +1.3 Above normal 4b 8 2nd lowest 185b 112 Above normal
Dunedin 11.3 +2.0 Highest on record 12 22 Well below normal 194 150 Equal highest
a Owairaka b Christchurch Airport

HIGHLIGHTS AND EXTREME EVENTS

- Temperature
Maximum temperatures exceeded 20 0 °C in many eastern regions from 21 through 26 September. The highest temperature during September 2006 was 25.0 °C recorded in Napier on the 22nd. The lowest air temperature for the month was -5.6 °C recorded at Hanmer Forest on the 11th.

Extremely high September maximum temperatures were recorded at:

Location Maximum temperature (°C) Date Year Records began Comments
Napier, Nelson Park 25.0 22 Sep. 1868 -
Gisborne Airport 24.9 26 Sep. 1905 3rd highest
Dunedin Airport 24.9 25 Sep. 1963 Highest
Queenstown 24.3 25 Sep. 1871 Highest
Whakatane Airport 23.8 24 Sep. 1975 2nd highest
Invercargill Airport 23.1 25 Sep. 1905 2nd highest

- High winds
A wind gust of 180 km/h from the northwest was recorded at Southwest Cape (Stewart Island) on the 2nd, a new record for a wind gust at that site (measurements which commenced in 1992). Mean wind speeds reached 128 km/h.

- High rainfall
There were several high rainfall events, with at least 50 mm in 24 hours, during September. These were:

Date Region/s affected Locations with high rainfall Rainfall (mm)
1 Sep. Southern Lakes Manapouri, West Arm 88 (1-day)
4 Sep. Fiordland, Southern Alps Milford Sound 73 (1-day)
5 Sep. Westland Hokitika Airport 62 (1-day)
9 Sep. Auckland, Coromandel, East Cape Whitianga Airport 63 (1-day)
10 Sep. Northland Whangarei Airport 53 (1-day)
15 Sep. Fiordland Milford Sound 67 (1-day)
18-21 Sep. Fiordland, Southern Alps Milford Sound 294 (4-days)
23 Sep. Fiordland, Southern Alps Milford Sound 50 (1-day)
25 Sep. Fiordland Milford Sound 115 (1-day)

ENDS

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