Climate Summary – February 2011: A tale of two islands

NATIONAL CLIMATE CENTRE Tuesday 1 March 2011

National Climate Summary – February 2011: A tale of two islands

• Rainfall: Extremely dry across most of the North Island. Record wet for central Otago, and above normal rainfall elsewhere in the southern half of the South Island.
• Temperatures: Very warm for much of the North Island. Monthly temperatures close to average over the South Island (except Nelson, Marlborough). Record-breaking heat between 2 and 7 February at many locations.
• Sunshine: Sunny for Northland and the northern South Island. Cloudy over the southern half of the South Island. Close to normal elsewhere.
• Soil moisture deficits: Remain significant in southern Taranaki, Manawatu, Kapiti coast, Wellington, Wairarapa, Nelson, Marlborough and north Canterbury.

Weather conditions were generally settled over the North Island during February 2011, with more northwest winds than usual over the South Island. It was an extremely dry February for parts of Northland and Auckland, the Central Plateau, parts of southern Hawkes Bay and the Wairarapa, and parts of Marlborough, with rainfalls less than 20 percent of February normal in these regions. It was the driest February in Dannevirke since records began there in 1951. Rainfall was also well below normal (less than 50 percent of February normal) across much of the North Island, as well as in Nelson. In contrast, it was a record wet month for central Otago, with more than double (200 percent) normal February rainfall experienced. Notably, much of this rain fell in a single extreme event on February 6th, along with record-breaking heat wave conditions. Elsewhere over the southern half of the South Island, rainfall was also above normal (between 120 and 150 percent of February normal). At the end of February, significant soil moisture deficit (deficit more than 110 mm) was evident in southern Taranaki, Manawatu, Kapiti coast, Wellington, Wairarapa, Nelson, Marlborough and north Canterbury.

Monthly mean temperatures were well above average (more than 1.2°C above average) across the North Island and in parts of Nelson and Marlborough. In contrast, monthly mean temperatures were close to February average (within 0.5°C of average) for the remainder of the South Island. The first half of February was scorching warm, with record-breaking heat experienced between 2 and 7 February at numerous locations over the entire length of the country – but cooler conditions prevailed in the second half of the month. Timaru recorded 41.3°C on the 6th, a new February and also all-time temperature record there since records began in 1885. The New Zealand national average temperature was 17.9°C (0.7°C above the 1971–2000 February average).

February sunshine totals were above normal (between 110 and 125 percent of February normal) in Northland and over the northern half of the South Island. In contrast, below normal sunshine totals (between 75 and 90 percent of February normal) were experienced over the southern half of the South Island. Elsewhere, sunshine totals in February were close to normal (within 10 percent of normal).

Further Highlights:
• The highest temperature recorded was 41.3°C recorded at Timaru (Gardens) on the 6th (a new February and also all-time record for Timaru).
• The lowest temperature recorded was 1.1°C recorded at Hanmer Forest on the10th.
• The highest 1-day rainfall of 245.2 mm occurred at Mt. Cook Hermitage on the 6th.
• The highest gust was 170.5 km/hr, recorded at Cape Turnagain on the 2nd.
• Of the six main centres, Tauranga was the warmest, driest and sunniest, and Dunedin was the coolest and wettest.

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RAINFALL: EXTREMELY DRY ACROSS MOST OF NORTH ISLAND. RECORD WET FOR OTAGO. ABOVE NORMAL RAINFALL OVER THE SOUTHERN HALF OF SOUTH ISLAND

It was an extremely dry February for parts of Northland and Auckland, the Central Plateau, parts of southern Hawkes Bay and the Wairarapa, and parts of Marlborough, with rainfalls less than 20 percent of February normal in these regions. It was the driest February in Dannevirke since records began there in 1951, with only 6 mm of rainfall recorded. Rainfall was also well below normal (less than 50 percent of February normal) across much of the North Island, as well as in Nelson. In contrast, it was a record wet month for central Otago, with more than double (200 percent) normal February rainfall experienced. Notably, much of this rain fell in a single extreme event on February 6th, along with record-breaking heat wave conditions. Elsewhere over the southern half of the South Island, rainfall was also above normal (between 120 and 150 percent of February normal).

At the end of February, significant soil moisture deficit (deficit more than 110 mm) was evident in southern Taranaki, Manawatu, Kapiti coast, Wellington, Wairarapa, Nelson, Marlborough and north Canterbury.

Record or near-record February rainfall totals were recorded at:

Location / Rainfall total (mm) / Percentage of normal / Year records began / Comments
Ranfurly / 106 / 304 / 1943 / 3rd-highest
Lumsden / 115 / 149 / 1982 / 2nd-highest
Cromwell / 73 / 228 / 1949 / 3rd-highest
Alexandra / 99 / 328 / 1983 / Highest
/ / / /
Kaitaia / 14 / 16 / 1967 / 4th-lowest
Kerikeri / 32 / 35 / 1981 / 3rd-lowest
Tauranga / 9 / 13 / 1898 / 2nd-lowest
Taupo / 2 / 3 / 1949 / 2nd-lowest
Pukekohe / 9 / 12 / 1944 / 2nd-lowest
Turangi / 11 / 11 / 1968 / 4th-lowest
Masterton / 12 / 20 / 1926 / 4th-lowest
Dannevirke / 6 / 9 / 1951 / Lowest
Ohakune / 2 / 2 / 1961 / 2nd-lowest
Waiouru / 11 / 18 / 1950 / 3rd-lowest
Wanganui / 17 / 26 / 1987 / 3rd-lowest
Appleby / 5 / 9 / 1941 / 4th-lowest

TEMPERATURES: VERY WARM FOR MUCH OF NORTH ISLAND. MONTHLY TEMPERATURES CLOSE TO AVERAGE FOR SOUTH ISLAND (EXCEPT NELSON AND MARLBOROUGH). RECORD HEAT BETWEEN 2 AND 7 FEBRUARY AT MANY LOCATIONS.

Monthly mean temperatures were well above average (more than 1.2°C above average) across the North Island and in parts of Nelson and Marlborough. It was the warmest February on record at Tauranga since records began in 1913, with a mean monthly temperature of 21.7°C. In contrast, monthly mean temperatures were close to February average (within 0.5°C of average) for the remainder of the South Island. The first half of February was scorching warm, with record-breaking heat experienced between 2 and 7 February at numerous locations over the entire length of the country – but cooler conditions prevailed in the second half of the month. Timaru recorded 41.3°C on the 6th, a new February and also all-time temperature record there since records began in 1885, and many sites recorded temperatures in excess of 30.0°C on the 5th and 6th. The New Zealand national average temperature was 17.9°C (0.7°C above the 1971–2000 February average) [Interim monthly value.].

Maximum temperatures were record high for February in parts of Auckland and in Nelson, and near-record high in the Bay of Plenty, Gisborne, Wanganui, Marlborough and in Timaru.

Record or near-record high February mean maximum air temperatures were recorded at:

Location / Mean maximum air temperature (°C) / Departure from normal (°C) / Year records began / Comments
Kerikeri / 26.0 / 1.3 / 1981 / 4th-highest
Kaikohe / 25.8 / 2.5 / 1973 / 2nd-highest
Leigh / 25.8 / 2.9 / 1966 / Highest
Whangaparaoa / 25.0 / 2.5 / 1982 / Highest
Tauranga / 26.0 / 2.0 / 1913 / 3rd-highest
Te Puke / 25.8 / 2.1 / 1973 / 3rd-highest
Whakatane / 25.9 / 1.5 / 1974 / 2nd-highest
Ngawi / 23.5 / 1.7 / 1972 / 4th-highest
Hicks Bay / 23.9 / 1.6 / 1969 / 3rd-highest
Mahia / 23.4 / 1.9 / 1990 / 3rd-highest
Wanganui / 24.4 / 1.7 / 1937 / 4th-highest
Takaka / 25.1 / 2.4 / 1978 / 2nd-highest
Motueka / 25.7 / 2.5 / 1956 / Highest
Appleby / 24.1 / 1.7 / 1943 / 2nd-highest
Nelson / 24.2 / 1.9 / 1943 / Highest
Timaru / 23.4 / 2.7 / 1885 / 3rd-highest

Record or near-record high February mean minimum daily air temperatures were recorded at:

Location / Mean minimum air temperature (°C) / Departure from normal (°C) / Year records began / Comments
Kaitaia / 16.6 / 1.4 / 1985 / 4th-highest
Kaikohe / 16.6 / 1.9 / 1973 / 4th-highest
Whenuapai / 16.6 / 2.4 / 1945 / 2nd-highest
Whitianga / 16.7 / 2.6 / 1962 / 3rd-highest
Te Puke / 15.6 / 2.0 / 1973 / 4th-highest
Whakatane / 16.0 / 1.9 / 1974 / 4th-highest
Taupo / 14.0 / 2.6 / 1949 / 4th-highest
Auckland / 17.9 / 1.6 / 1959 / 4th-highest
Martinborough / 14.0 / 1.9 / 1986 / 3rd-highest
Gisborne / 16.3 / 2.5 / 1905 / 3rd-highest
Hastings / 15.7 / 1.9 / 1965 / 2nd-highest
Waipawa / 13.8 / 1.9 / 1945 / 4th-highest
Wairoa / 15.7 / 2.0 / 1964 / 3rd-highest
Mahia / 16.5 / 1.4 / 1990 / 2nd-highest
Hawera / 14.1 / 1.9 / 1977 / 3rd-highest
Ohakune / 11.9 / 2.6 / 1962 / 2nd-highest
Waiouru / 10.9 / 2.3 / 1962 / 4th-highest
Wanganui / 15.4 / 1.2 / 1987 / 4th-highest
Farewell Spit / 15.4 / 1.8 / 1971 / 4th-highest

SUNSHINE: SUNNY FOR NORTHLAND AND THE NORTHERN SOUTH ISLAND. CLOUDY OVER THE SOUTHERN HALF OF THE SOUTH ISLAND. CLOSE TO FEBRUARY NORMAL ELSEWHERE.

February sunshine totals were above normal (between 110 and 125 percent of February normal) in Northland and over the northern half of the South Island. In contrast, below normal sunshine totals (between 75 and 90 percent of February normal) were experienced over the southern half of the South Island. For the remainder of the North Island, sunshine totals in February were close to normal (within 10 percent of normal).

Record or near-record February sunshine hours were recorded at:

Location / Sunshine (hours) / Percentage Of normal / Year records began / Comments
Kaitaia / 252 / 128 / 1985 / 2nd-highest
Takaka / 247 / 114 / 1985 / 3rd-highest
/ / / /
Cromwell / 191 / 89 / 1979 / 4th-lowest

FEBRUARY CLIMATE IN THE SIX MAIN CENTRES

Of the six main centres, for the month of February 2011 as a whole, Tauranga was the warmest, driest and sunniest, and Dunedin was the coolest and wettest. Mean temperatures were record high at Tauranga, being the highest mean February value since records began there in 1913. It was also an extremely dry February at both Auckland and Tauranga, with equal-3rd lowest and 2nd lowest February rainfalls recorded, respectively.

February 2011 main centre climate statistics:
Location / Mean temp. (°C) / Departure from normal (°C) / / Rainfall (mm) / % of normal / / Sunshine (hours) / % of normal /
Aucklanda / 21.3 / +1.4 / Well above average / 11 / 15% / Equal 3rd lowest since 1959 / 202 / 101% / Normal
Taurangab / 21.7 / +2.2 / Record high since 1913 / 9 / 13% / 2nd lowest since 1898 / 211 / 100% / Normal
Hamiltonc / 20.2 / +1.6 / Well above average / 34 / 55% / Below normal / 175 g / 88% / Below normal
Wellingtond / 17.7 / +0.6 / Above average / 28 / 45% / Well below normal / 207 / 99% / Normal
Christchurche / 17.0 / +0.2 / Average / 35 / 86% / Near normal / 198 / 101% / Normal
Dunedinf / 15.2 / +0.0 / Average / 109 / 177% / Well above normal / 133 / 87% / Below normal
a Mangere b Tauranga Airport c Hamilton Airport d Kelburn e Christchurch Airport f Musselburgh g Ruakura

HIGHLIGHTS AND EXTREME EVENTS

Rain and slips

On 2 February, flooding closed SH73 between Jacksons and Kumara Junction with a detour via Moana. On 3 February, one lane of SH25 was closed by a slip at Waikawau.

The highest 1-day rainfall recorded in February 2011 was 245.2 mm, observed at Mt Cook Hermitage on the 6th. On the same day, extreme rainfalls were experienced in Otago and Southland (see table below). During the 6 - 7 February event, heavy rain caused flooding in West and South Otago, with some roads impassable, and surface flooding over large areas of farmland, especially around Kelso and low-lying parts of Balclutha. SH90 was closed near Tapanui, and two slips on the Haast Pass Highway, one southwest of Makarora, and another west of the summit, closed the road during the morning. In Timaru, the heavy rain brought down a tree which hit the 11kV power line, cutting power to homes southwest of the city. On 8 February, the Land Transport Authority closed the twin bridges over the Waitaki River at Kurow, after high river flows damaged a bridge pier.

Record or near record high extreme 1-day rainfall totals were recorded at:

Location / Extreme 1-day rainfall (mm) / Date of extreme rainfall / Year records began / Comments
Tara Hills / 40 / 6th / 1949 / 3rd-highest
Ranfurly / 53 / 6th / 1943 / Highest
Dunedin / 54 / 6th / 1962 / 3rd-highest
Lumsden / 57 / 6th / 1982 / Highest
Cromwell / 52 / 6th / 1949 / Highest
Alexandra / 68 / 6th / 1983 / Highest
Gore / 64 / 6th / 1967 / Highest
Invercargill / 54 / 6th / 1939 / 3rd-highest
Tiwai Point / 42 / 6th / 1970 / 2nd-highest
Balclutha / 73 / 6th / 1964 / 2nd-highest
Nugget Point / 63 / 6th / 1930 / Highest

• Temperature

Record-breaking heat was experienced at numerous locations covering the entire length of the country between 2 and 7 February. Records were broken for February for both morning minimum and afternoon maximum temperatures (see tables below and overleaf). Timaru recorded 41.3°C on the 6th, a new February and all-time record there since records began in 1885. Many sites recorded temperatures in excess of 30.0°C during February 5 and 6.

Record or near-record daily maximum air temperatures were recorded at:
Location / Extreme maximum temperature (ºC) / Date of extreme temperature / Year Records Began / Comments
Kerikeri / 29.2 / 3rd / 1981 / Equal 3rd-highest
Kaikohe / 29.8 / 5th / 1973 / 3rd-highest
Leigh / 29.5 / 5th / 1966 / 2nd-highest
Whangaparaoa / 27.9 / 5th / 1982 / 2nd-highest
Tauranga / 30.7 / 5th / 1913 / Equal 4th-highest
Te Puke / 31.2 / 5th / 1973 / Highest
Ngawi / 30.6 / 6th / 1972 / 3rd-highest
Hicks Bay / 28.2 / 4th / 1969 / Equal 2nd-highest
Gisborne / 36.3 / 2nd / 1905 / 2nd-highest
Hastings / 33.8 / 7th / 1965 / 4th-highest
Wairoa / 34.5 / 2nd / 1964 / 3rd-highest
Mahia / 30.3 / 2nd / 1990 / 3rd-highest
Hawera / 27.4 / 7th / 1977 / Equal 3rd-highest
Wanganui / 28.6 / 22nd / 1987 / 2nd-highest
Takaka / 33.0 / 6th / 1978 / Highest
Motueka / 32.9 / 6th / 1956 / 2nd-highest
Nelson / 31.0 / 2nd / 1943 / 3rd-highest
Appleby / 29.8 / 2nd / 1943 / 4th-highest
Nelson / 30.2 / 2nd / 1943 / 3rd-highest
Blenheim / 34.1 / 6th / 1932 / 2nd-highest
Kaikoura / 34.3 / 2nd / 1963 / Highest
Christchurch / 35.9 / 6th / 1863 / 3rd-highest
Le Bons Bay / 30.8 / 2nd / 1984 / 3rd-highest
Lake Tekapo / 32.7 / 6th / 1925 / 2nd-highest
Orari / 36.0 / 6th / 1972 / 4th-highest
Timaru (Aero) / 40.3 / 6th / 1990 / Highest
Timaru (Gardens) / 41.3 / 6th / 1885 / Highest
Oamaru / 35.8 / 6th / 1908 / 2nd-highest
Dunedin / 34.4 / 6th / 1947 / 3rd-highest
Lumsden / 30.3 / 6th / 1982 / 2nd-highest
Alexandra / 34.7 / 6th / 1983 / 3rd-highest
/ / / /
Kerikeri / 18.6 / 9th / 1981 / 3rd-lowest

Record or near-record daily minimum air temperatures were recorded at:
Location / Extreme minimum temperature (ºC) / Date of extreme temperature / Year records began / Comments
Whangaparaoa / 20.2 / 5th / 1982 / Equal 3rd-highest
Whitianga / 21.2 / 5th / 1971 / Equal 2nd-highest
Paeroa / 21.2 / 5th / 1971 / Equal 4th-highest
Tauranga / 21.5 / 4th / 1941 / Equal 4th-highest
Te Puke / 20.8 / 4th / 1973 / 3rd-highest
Rotorua / 20.3 / 4th / 1972 / Highest
Taupo / 19.7 / 5th / 1950 / 3rd-highest
Port Taharoa / 20.5 / 14th / 1974 / 4th-highest
Turangi / 18.7 / 5th / 1968 / 4th-highest
Takapau Plains / 20.0 / 6th / 1972 / Equal 3rd-highest
Castlepoint / 21.5 / 6th / 1972 / Equal 3rd-highest
Martinborough / 22.1 / 6th / 1986 / 2nd-highest
Ngawi / 21.7 / 7th / 1972 / 4th-highest
Wallaceville / 19.2 / 7th / 1972 / Equal 4th-highest
Hawera / 19.6 / 4th / 1977 / Equal 2nd-highest
Ohakune / 17.8 / 5th / 1972 / 4th-highest
Waiouru / 16.9 / 4th / 1972 / Equal 3rd-highest
Wanganui, / 20.4 / 5th / 1972 / 2nd-highest
Lake Rotoiti / 16.9 / 7th / 1972 / 3rd-highest
Reefton / 20.4 / 7th / 1972 / Highest
Hanmer Forest / 23.5 / 6th / 1972 / 2nd-highest
Arthurs Pass / 16.3 / 7th / 1973 / 2nd-highest

Wind

The highest gust observed during February 2011 was 170.5 km/hr, recorded at Cape Turnagain on the 2nd.

On 2 February, record-breaking westerly winds occurred over the South Island and around central New Zealand (see table below). High winds and low cloud prevented the Canterbury Crusaders rugby team flying to Hokitika. The northwest winds also knocked down trees, damaging a 33 KV power line, cutting power to about 2500 homes near Leeston. In Fairlie, 15 power poles were snapped, cutting power to the town. SH80 between Lake Pukaki and Mt Cook, and SH8 between Fairlie and Twizel were closed to towing vehicles. Cautions were also in place for SH1 between Blenheim and Cheviot, and SH73 between Springfield and Arthurs Pass. In Te Anau, a mini-tornado ripped corrugated iron off classroom roofs at Fiordland College, flinging one sheet up to 150 m over trees and across a sports field.

On 8 February, high winds affected SH8 from Fairlie to Twizel, and SH80 from Pukaki to Mt Cook, with warnings in place for high-sided vehicles.

Near-record high extreme wind gusts for February were recorded at:

Location / Extreme wind gust speed (km/hr) / Date of extreme gust / Year records began / Comments
Castlepoint / 154 / 2nd / 1972 / 2nd-highest
Puysegur Point / 146 / 2nd / 1986 / 4th-highest
Tara Hills / 87 / 2nd / 1985 / 4th-highest
Lauder / 100 / 2nd / 1981 / 3rd-highest
Gore / 117 / 2nd / 1987 / Highest

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