October 2003

Saturday, 1 November 2003

Rainfall: Near or above average over much of the North Island; below average in Hawke’s Bay, Westland, Fiordland, Canterbury, Otago and Southland

Temperatures: Below average temperatures over much of the North Island, and the eastern South Island (Marlborough, Canterbury and Otago)

Sunshine: above average in most regions, especially Southland

October was a month of mixed weather. It was wet and rather unsettled in many areas during the first two weeks. However, mainly dry settled conditions prevailed for the rest of the month. The month’s rainfall was well above average in parts of Northland, Coromandel, Bay of Plenty, Wairarapa and Wellington, and well below average in Hawke’s Bay, inland south Canterbury and the Southern Lakes. Soil moisture deficits are increasing throughout Otago and South Canterbury, being significant in some inland areas there. Deficits are also appearing in Marlborough, and Hawke’s Bay. The month was cooler than usual over much of the North Island and the eastern South Island. Sunshine totals were above average throughout much of New Zealand. The October climate patterns were associated with more frequent depressions (‘lows’) than usual in the north Tasman Sea off the Australian coast, with more frequent easterlies and northeasterlies over much of New Zealand. More anticyclones (‘highs’) prevailed to the southeast so that westerlies were noticeably less frequent than normal.

Highlights

• The lowest air temperature for October 2003 was –6.9°C, recorded at The Chateau, Tongariro, on the 6th, along with other frosts and unusually low temperatures on the same day in many other North Island and southern South Island areas. Some Bay of Plenty kiwifruit orchards and Marlborough stone fruit orchards were affected by frosts. The highest air temperature for the month was 27.0°C, recorded at Alexandra on the 20th.
• A severe high intensity rainfall event producing 200–300 mm in the Tararuas, along with gale force northerly winds, occurred on 3 October, contributing to a devastating land and mudslide at Paekakariki, followed by significant snow to high country areas in and near the Canterbury foothills; thousands of lambs were lost due to exposure.
• Christchurch was the driest of the four main centres, and Wellington the wettest. Rainfall was above average in Auckland and Wellington, and near average in Christchurch and Dunedin. Mean temperatures were near average in Wellington, but below average in the other centres, especially Christchurch. Sunshine hours were above average in Christchurch and Dunedin, and near average in Auckland and Wellington.

Rainfall

Rainfall was near or above average over much of the North Island and northern South Island regions, and below or near average throughout the South Island. Parts of Northland, Coromandel, Bay of Plenty, Wairarapa and Wellington recorded about 200 percent (double) of average rainfall, while totals were 75 percent or less (three quarters) of average in Hawke’s Bay, inland south Canterbury and the Southern Lakes, Westland, and Fiordland. Near average rainfall occurred elsewhere.

Temperatures

Mean temperatures were at least 0.5°C below average throughout most of the North Island and the east of the South Island from coastal Marlborough to Otago, but near average in south Taranaki, Buller, Nelson, Buller, Westland, Fiordland and much of Southland. The October national average temperature of 11.8°C was 0.3°C below normal.

Sunshine

Sunshine totals were above average throughout much of New Zealand, especially Southland. Sunshine was near normal in Northland and Auckland.

Near or above average rainfall over much of the North Island

Below or near average rainfall throughout the South Island

October rainfall was near or above average over much of the North Island and northern South Island regions, and below or near average over much of the South Island. Northland, Coromandel, Bay of Plenty, Wairarapa and Wellington all recorded between 125 and 225 percent (one and a quarter to two and a quarter) of average rainfall. Contrasting well below average rainfall occurred in inland south Canterbury and the Southern Lakes, all with totals 50 percent (half) or less of average. Rainfall was less than 75 percent of average in Hawke’s Bay, Westland, Fiordland, and much of Southland and Otago. Rainfall was near average elsewhere.

Near or record high October rainfall was recorded at:

Location	October rainfall (mm)	Percentage of normal	Year records began	Comments
Whakatane Airport	204	204	1975	Well above normal
Motu	392	233	1991	Highest
East Taratahi	118	183	1972	Well above normal
Palliser, Ngawi	171	248	1930	Well above normal

Very low October rainfall was recorded at:

Location	October rainfall (mm)	Percentage of normal	Year records began	Comments
Tekapo	12	23	1925	Well below normal

Cooler over much of the North Island and eastern South Island

Mean temperatures were at least 0.5°C below average throughout most of the North Island and the east of the South Island from coastal Marlborough to Otago. Temperatures were at least 1.0°C below average in parts of Auckland, Gisborne, Hawke’s Bay, coastal areas of Wairarapa and Wanganui, the Christchurch area and parts of Central Otago. Temperatures were near average in south Taranaki, Buller, Nelson, Buller, Westland, Fiordland and much of Southland.

Near record low October air temperatures were recorded at:

Location	Mean temperature	Departure from average (°C)	Records began	Comments
Auckland, Henderson	13.2	–1.8	1986	3rd lowest

Sunnier in most regions, especially Southland

Sunshine totals were above average (at least 110 percent of normal) throughout much of New Zealand, especially in Southland. Sunshine was near normal in Northland and Auckland.

High October sunshine was recorded at:

Location	October sunshine (hours)	Percentage of normal	Year records began	Comments
Taumarunui	192	129	1947	Well above normal
Dunedin	194	126	1948	4th equal highest
Invercargill	208	133	1932	3rd highest

October climate in the four main centres

Of the four main centres, Christchurch was the driest, with 48 mm. August rainfall was above average in Auckland and Wellington, and near average in Christchurch and Dunedin. Mean temperatures were near average in Wellington, but below average in the other centres, especially Christchurch. Sunshine hours were above average in Christchurch and Dunedin, and near average in Auckland and Wellington.

	Aucklanda	Wellington	Christchurchb	Dunedin
October mean temp. (°C)	13.2	11.9	10.5	10.0c
Dep. from normal (°C)	–0.8	–0.2	–1.4	–0.4
	Below average	Near average	Well below average	Below average
October rainfall (mm)	127	150	48	55c
% of normal	136	152	108	92
	Above average	Above average	Near average	Near average
October sunshine (hours)	183d	192	235	No data
% of normal	96	98	115	–
	Near average	Near average	Above average	Above average

a Mt Albert, b Christchurch Airport, c Dunedin Airport, d Whenuapai

Highlights and extreme events

• The lowest air temperature for October 2003 was –6.9°C, recorded at The Chateau on the 6th, and –6.8°C at Waiouru. The latter was the lowest on record there in October, in records that commenced in 1966. Other unusually low air temperatures also occurred (mainly on the 6th) at the following locations:

  Location	Min. (°C)	Date	Records Began	Comments
  Te Puke	0.0	6	1973	2nd lowest
  Gisborne Airport	–0.4	6	1905	2nd equal lowest
  Rotorua Airport	–1.9	6	1964	2nd lowest
  Waiouru	–6.8	6	1966	Lowest
  Palmerston N. Airport	–1.6	6	1963	3rd lowest
  Hanmer Forest	–5.5	6	1906	Lowest
  Wanaka Airport	–2.9	6	1992	Lowest
  Queenstown Airport	–3.7	6	1968	Lowest
  Ranfurly	–4.8	5	1975	3rd lowest

  Near or record low October grass minimum temperatures were recorded at:

  Location	Grass min. (°C)	Date	Records began	Comments
  Motueka, Riwaka	–5.0	6	1956	3rd lowest
  Mt. Cook Village	–9.6	6	1931	2nd lowest
  Winchmore	–7.9	6	1950	3rd lowest

• The highest air temperature for October 2003 was 27.0°C, recorded at Alexandra on the 20th.
• High intensity rainfall associated with the approach of an active frontal system occurred on 3 October, after weeks of wet weather, contributing to a huge land and mudslide across SH1 at Pakekakariki. Exceptionally high 48-hour rainfall totals in excess of 200–300 mm were recorded in the Tararua Ranges over 3–4 October. Other high rainfall totals, exceeding 100 mm, recorded during the event of 3 October were:

  Location	Rainfall (mm)
  Motu	177
  Taumarunui	101
  Stratford	116
  Paekakariki Hill	119
  Wallaceville	108

  Gale force northerly winds (with gusts between 130 and 140 km/h in and about Cook Strait) and high seas accompanied the rainfall.

• This resulted in the closure of state highway and main trunk railway north of Wellington. Other routes out of Wellington were also closed, and the cancellation of two inter-island ferry crossings occurred. Two people were killed in a freight plane, possibly hit by lightning, as it crashed in the sea off the Kapiti coast. Farther south, a man drowned at sea off the Kaikoura coast. In the north, a woman was swept downstream in a flooded ford near Coroglen (in the Coromandel) on the 4th. A state of emergency was declared in Paekakariki as sewage and contaminated mud and water (up to waist deep) spread through houses, of which more than 20 were evacuated and 8 left uninhabitable. Almost every business in Paekakariki was flooded, and several cars were covered by mud and rubble. Around 10,000 cu m of gravel poured down Paekakariki Hill during the event. Initial damages due to the event were estimated to be at least $2.5 million for Paekakariki and another $3 million for the remainder of New Zealand. On the 4th snow occurred on the Rimutaka and Orongaronga ranges, and settled down to 800 m on the central North Island plateau, with flurries in Taihape, Taumarunui, and the Wellington hill suburbs of Brooklyn, Karori and Broadmeadows. On the 5th snow fell down to 200 m in the South Island high country of Canterbury, Otago, and Southland, where thousands of newborn lambs died due to exposure. A snow depth of 20 cm was reported at Oxford, near the Canterbury foothills. Snow closed part of SH1 north of Dunedin.
• Further high rainfall, totalling at least 70 mm occurred in Northland on the 11th, followed by rainfall totalling about 100 mm in eastern Bay of Plenty, the Gisborne high country and coastal areas of southern Wairarapa on the 12th.

For further information, please contact:

Dr Jim Salinger – Principal Scientist, Climate NIWA National Climate Centre – Auckland Phone +64 9 375 2053 [email protected]

Stuart Burgess – Climatologist NIWA National Climate Centre – Wellington Phone +64 4 386 0569 [email protected]

Geoff Baird – Communications Manager Phone +64 4 386 0543 [email protected]

Acknowledgement of NIWA as the source is required.