National Climate Summary – October 2005

NATIONAL CLIMATE CENTRE FRIDAY 4 NOVEMBER 2005

National Climate Summary – October 2005

- Rainfall: Above average in the North Island, below average over much of the South Island

- Soil moisture; Significant deficits developing in Marlborough, south Canterbury and much of Otago

- Temperature: Above average in the northern half of the North Island, below average in eastern regions

- Sunshine: Very sunny in Buller and Westland

- Flooding: Significant in the Gisborne region

Contrasting rainfall patterns between the North and South Islands were a highlight in October. Gisborne, Hawke’s Bay, Auckland and Waikato were extremely wet with new October records established in some centres, while much of the South Island was extremely dry. Rainfall in Gisborne and Hawke’s Bay, was at least 300 percent of (three times) normal, while parts of Nelson and Southern Lakes, south Westland, Fiordland, and inland South Canterbury all had less than 50 percent of (half) normal. Significant soil moisture deficits are developing in Marlborough, south Canterbury and much of Otago. Temperatures were above average in the northern half of the North Island, and below average in many eastern regions. The national average temperature of 12.0 °C was 0.1 °C below normal. October was very sunny in Buller and Westland. Higher than normal air pressures to the south of New Zealand producing more easterly quarter air flow than usual over New Zealand.

Other Highlights:

- The highest temperature during October 2005 was 27.0 °C recorded at both Alexandra on the 26th, and Woodbury on the 27th. The lowest temperature for the month was -5.1°C at Ranfurly on the 6th.

- The highest wind gust for the month was 132 km/h from the northwest, recorded at Castlepoint on the 1st. Damaging westerly gales affected Northland and Auckland on the 8th, and a tornado affected parts of Auckland city on the 11th. Damaging high winds also occurred near Matamata on the 15th.

- A major rainfall event produced rainfall totals of 55 to 85 mm throughout much of Northland, Auckland, Coromandel, Bay of Plenty on the 20th, spreading to Gisborne and Hawke’s Bay the next day; Gisborne Airport recording 148 mm for the 24 hours to 9am on the 22nd, and Motu 134 mm, with 93 mm at Napier Airport. More than 300 mm of rainfall was reported in some inland hill country areas north of Gisborne. There were extensive crop losses and damage to roads on the Tologa and Poverty Bay plains. About 50 homes were evacuated, and the water supply affected. Mangatuna was the worst affected area.

- A hailstorm affected parts of Hawke’s Bay on the 5th. Further damaging hailstorms affected parts of Gisborne and Hawke’s Bay on the 17th. Pea sized hail occurred in Wairarapa on the 30th.

- Of the four main centres Dunedin was the driest and Auckland the wettest, while Wellington was the sunniest. Rainfall was a record October high in Auckland, near average in Christchurch, and below average in Wellington and Dunedin. Temperatures were slightly above average in Auckland and Wellington, but below average in the other main centres. Sunshine hours were well above average in Wellington and Dunedin, near average in Auckland and below average in Christchurch.

Rainfall: Rainfall was above average over much of the North Island, especially in Gisborne and Hawke’s Bay, with more than 300 percent (triple) of normal, and parts of Auckland, Waikato, Bay of Plenty, Taupo, and Wairarapa, and at least 200 percent (double) of normal. Rainfall was below average over much of the South Island, and in Horowhenua and Wellington.

Temperature: Mean temperatures were above average in much of Northland, Auckland, Waikato, and Bay of Plenty. However, they were below average in many eastern regions from Hawke’s Bay to coastal Otago. Temperatures were near average elsewhere.

Sunshine: Sunshine hours were at least 150 percent of average in Buller and Westland, at least 120 percent of average in Manawatu, Kapiti, Wellington, Nelson, coastal Otago, and Southland. It was also sunnier than average in Taranaki, and inland south Canterbury.

WET OVER MUCH OF THE NORTH ISLAND, ESPECIALLY GISBORNE AND HAWKE’S BAY

WELL BELOW AVERAGE RAINFALL IN SOUTH WESTLAND, FIORDLAND AND INLAND SOUTH CANTERBURY

Rainfall was at least 125 percent of normal rainfall over much of the North Island, at least 200 percent of normal in parts of Auckland, Waikato, Bay of Plenty, Taupo, and Wairarapa, and more than 300 percent of normal in Gisborne and Hawke’s Bay. In contrast, rainfall was below average over much of the South Island, and in Horowhenua and Wellington, with less than 75 percent of normal in many places. Rainfall was less than 50 percent of normal in parts of Nelson, Southern Lakes, south Westland, Fiordland, and inland South Canterbury. Rainfall was near average along the Canterbury coast.

Near or record high October rainfall was recorded at:

Location October Rainfall (mm) Percentage of normal Year records began Comments

Whangaparaoa 162 217 1987 Highest

Auckland, Henderson 193a 177 1986 Highest

Auckland, Owairaka 209 229 1949 Highest

Whitianga Airport 246 193 1990 Highest

Tauranga Airport 193 204 1898 Well above average

Te Puke 313 228 1973 2nd equal highest

Whakatane Airport 216 215 1975 3rd highest

Taupo Airport 174 192 1976 3rd highest

Motu 284 159 1991 2nd highest

Auckland Airport 180 218 1962 2nd highest

Hamilton Airport 202 204 1935 2nd highest

Waione 176 200 1996 2nd highest

Gisborne Airport 225 356 1905 2nd highest

Napier Airport 194 328 1950 2nd highest

Whakatu 155 318 1983 2nd highest

Mahia 202 244 1991 Highest

a to 28 October

Near or record low October rainfall was recorded at:

Location October Rainfall (mm) Percentage Of normal Year records began Comments

Takaka 69 28 1986 Lowest

Franz Josef 218 31 1982 3rd lowest

Manapouri Airport 38 30 1991 2nd lowest

TEMPERATURES ABOVE AVERAGE OVER THE NORTHERN HALF OF THE NORTH ISALND; BELOW AVERAGE IN MANY EASTERN REGIONS

Mean temperatures were about 0.5 °C above average in much of Northland, Auckland, Waikato, and Bay of Plenty. However, they were about 0.5 °C below average in eastern regions from Hawke’s Bay to coastal Otago, and about 1.0 °C below average in inland parts of south Canterbury. Temperatures were near average elsewhere. The national average temperature was 12.0 °C, 0.1 °C below average.

VERY SUNNY AVERAGE IN BULLER AND WESTLAND

Sunshine hours were at least 150 percent of average in Buller and Westland, at least 120 percent of average in Manawatu, Kapiti, Wellington, Nelson, coastal Otago, and Southland, and more than 110 percent of average in Taranaki, and inland south Canterbury. Hours of bright sunshine were near average elsewhere.

Near or record October sunshine hours were recorded at:

Location October sunshine (hours) Percentage of normal Year Records began Comments

Arapito 214a 154 1979 Highest

Hokitika Airport 243 155 1912 2nd highest

a to 30 October

OCTOBER’S CLIMATE IN THE FOUR MAIN CENTRES

Of the four main centres Dunedin was the driest and Auckland the wettest, while Wellington was the sunniest. Rainfall was the highest on record for October in Auckland, near average in Christchurch, and below average in Wellington and Dunedin. Temperatures were slightly above average in Auckland and Wellington, but below in the other main centres. Sunshine hours were well above average in Wellington and Dunedin, near average in Auckland and below average in Christchurch.

Location Oct. Mean Temp. (°C) Dep. from normal (°C) Oct. rainfall (mm) % of normal Oct. Sunshine (hours) % of Normal

Auckland 14.6a +0.2 Near average 209b 229 Highest 170a 95 Near average

Wellington 12.3 +0.3 Above average 85 74 Below average 232 120 Well above average

Christchurch 10.8c -0.9 Below average 43c 88 Near average 172 87 Below average

Dunedin 10.4 -0.5 Below average 24 33 Well below average 178 121 Well above average

a Mangere b Mt Albert c Christchurch Airport

HIGHLIGHTS AND EXTREME EVENTS

- Temperature

The highest temperature during October 2005 was 27.0 °C recorded at both Alexandra on the 26th, and Woodbury on the 27th. The lowest temperature for the month was -5.1°C at Ranfurly on the 6th.

- Rainfall

Rainfall totalling 70-80 mm was recorded in Western Bay of Plenty on the 2nd.

A major rainfall event produced rainfall totals of 55 to 85 mm throughout much of Northland, Auckland, Coromandel, Bay of Plenty on the 20th, spreading to Gisborne and Hawke’s Bay the next day; Gisborne Airport recording 148 mm for the 24 hours to 9am on the 22nd, and Motu 134 mm, with 93 mm at Napier Airport. However, more than 300 mm of rainfall was reported in the inland hill country in areas north of Gisborne. There were extensive crop losses (affecting about 3000 ha of horticultural land), and damage to roads on the Tologa and Poverty Bay plains. About 50 homes were evacuated, and the water supply cut off. The Mangatuna settlement appeared to be the worst affected area. The cost of the damage and losses is estimated to be in the millions.

- Hailstorms

A hailstorm affected parts of Hawke’s Bay (Mangateretere and Whakatu) at about 2.30pm on the 5th, damaging summer fruit crops. Most of the hailstones were described as pea-sized, which lasted for 10 minutes. Hail was still lying on the ground at 5pm. Further hailstorms affected parts of Gisborne (Te Karaka) during the afternoon on the 17th, some hail stones estimated to be the size of small golf balls, and also Hawke’s Bay with crops in some orchards damaged. Pea sized hail occurred in Wairarapa on the 30th. These were associated with thunderstorms which produced torrential rainfall, totalling 22 mm in 10 minutes and 32 mm in an hour, in Masterton.

- High winds

The highest wind gust for the month was 132 km/h from the northwest, recorded at Castlepoint on the 1st.

During gale force westerlies and rough seas on the 8th, a 3000-tonne container ship crashed into Auckland’s old Mangere Bridge, and about 20 boats were blown off their moorings,. Trees were felled, power lines broken, and roofs lifted in the city, with power cuts for about 17,500 residents. Gusts to 150 km/h were noted at Tiri Tiri Matangi lighthouse, and 100 km/h at Auckland Airport. Lightning strikes also caused power outages affecting people as far north as Wellsford. The same weather system resulted in fallen trees in Northland, and snowfall on the Desert Road, and 15 cm of snow in Arthurs Pass, Lewis Pass and Porters Pass.

A tornado affected parts of Auckland city just after 1am, including Western Springs, Kingsland, and Morningside on the 11th, resulting in damaged roofs. High winds, also attributed to a tornado, damaged an Okorore barn, trees, fences and power lines near Matamata on the 15th.

ENDS