2008

Tuesday, 13 January 2009

2008: sunny and warm, but a rollercoaster year for extremes.

New Zealand’s climate for 2008 was sunny and warm, but a rollercoaster year for extremes, according to NIWA’s National Climate Centre.

It was sunny or very sunny over much of the country, with near record or record sunshine totals recorded in the central North Island, parts of Hawke’s Bay and the south of the South Island.  The national average temperature was of 12.9°C during 2008, milder than normal. This was a result of five warm months with above average temperatures for the country as a whole and only one with below average temperatures. Temperatures were between 0.5 and 1.0°C above average in the west of the North Island and Nelson, and up to 0.5 °C above average in most other regions. Rainfall during the year was 135 percent of normal or more in Wellington and central Marlborough. Only in parts of Fiordland and southern Hawke’s Bay were annual rainfall totals 80 percent of normal or less.

Notable climate features in various parts of the country were the economically disastrous drought in the west of the North Island in the first part of the year (estimated costs of at least $1 billion), then floods in central North Island areas causing loss of life, damaging floods in July and August in Marlborough and Canterbury, and a significant snow storm in August followed by some unusual late spring snowstorms. The July and August events have estimated insurance costs of $68 million. By the end of the year, dry conditions had set in over the east of the country. It was a year with heat waves and many new records of high temperature extremes were established. Of the main centres, Wellington was extremely wet, and Dunedin very sunny and dry.

Over the year, the broad climate setting swayed from La Niña to neutral then back to La Niña. The start of the year was dominated by a significant La Niña event in the equatorial Pacific. This dissipated with neutral conditions during winter and early spring, but weak La Niña conditions redeveloped in the tropical Pacific by the end of the year.

The year in review

Broadly speaking, the picture of the year (with clear geographical exceptions) is:

  • January–March: very dry
  • April: extremes
  • May: cold
  • June–August: stormy
  • September: more settled
  • October–December: becoming dry again

January–March: very dry

In January, heat wave conditions occurred across inland areas of the South Island, and even extended to coastal parts of Canterbury and central Marlborough. Extremely low rainfall occurred in many areas, with monthly totals of less than 10 mm in the Hauraki Plains, Waikato, King Country, coastal Marlborough and parts of north Canterbury. In Waikato it was the driest January in over 100 years of records. The dryness continued through February (50% or less of normal rainfall over much of the North Island from Manukau southwards, and in coastal Otago and parts of Southland) and March (30 to 50% of normal rainfall fell throughout Canterbury, Fiordland, Auckland, Waikato, the King Country and eastern Wairarapa). As a result, severe soil moisture deficits persisted in Waikato, parts of Bay of Plenty, South Taranaki and northern Manawatu, Hawke’s Bay, Wairarapa, as well as Marlborough, and parts of south Canterbury, Otago and Southland.

April: extremes

April was a month of extremes with floods in northern New Zealand, while it remained dry in the south. Heavy rainfalls alleviated the severe and significant soil moisture deficits in most of the North Island.

May: cold

May was a cold month, with the national average temperature of 9.6°C being 1.1°C below average. This made it almost 4°C lower than mean air temperatures in April, and the coldest May since 1992

June–August: stormy

In contrast to May, June was much warmer than average in places especially inland South Canterbury and Otago. The weather got very boisterous in late June, with thunderstorms, hail, lightning and high winds affecting much of the North Island.

July and August were very wet in many parts of the country. In July, rainfall was well above normal (more than 200%) in Marlborough, Canterbury, and eastern Otago, with near record high July totals in many locations. In the last week of July New Zealand was hit by two intense storms which caused flooding, significant damage to property, resulted in several evacuations, and led to the deaths of five people. Rainfall totals were greater than one and a half times their normal values for much of the North Island in August, and Marlborough received over 300% of its normal August rainfall. There were several storms during August bringing a mixture of snow, high winds and heavy rainfall to much of the country. On Mt Ruapehu the recorded 3.5 m of snow pack was the deepest snow base since records began in 1992.

September: more settled

September brought a shift back to much more settled weather conditions for the country. Temperatures were above average for the country as a whole and well above average (more than 1.5°C above their normal values) in South Canterbury and Central Otago. Rainfall in September was below normal for many areas, particularly in parts of Northland, Auckland, Waikato, Coromandel, and the east coast of the North Island where less than 50% of normal rainfall fell.

October–December: becoming dry again

Sunshine totals were well above average for most of the South Island in October, with Dunedin and Balclutha recording their highest October values on record. Rainfall was less than 50% of normal (half) in Otago and coastal south Canterbury and between 50 and 80% of normal in parts of northern Canterbury, West Coast, Tasman, Wellington, Hawke’s Bay, Gisborne, Bay of Plenty and Northland. November and December were sunny months over much of the country and rainfall was once again less than 50% of normal in eastern areas of the country and between 50 and 80% of normal for the majority of the North Island. Soil moisture levels in eastern areas and in Waikato were between 30 and 50 mm lower than normal at the end of December. Double the normal rainfall for November fell in Tasman (mostly in two days) and for December in inland Canterbury and Banks Peninsula.

NIWA analyses of month-by-month records and preliminary end of year data show:

  • The highest annual mean temperature recorded for the year was 16.5°C at Leigh.
  • The highest recorded extreme temperature of the year occurred in South Canterbury being 34.8 °C recorded at Timaru Airport on 12 January and 19 March and at Waione on 22 January in very hot dry northwesterly conditions.
  • The lowest air temperature for the year was -9.5 ºC recorded at Mt. Cook on 20th August.
  • The highest recorded wind gust for the year (as archived in the NIWA climate database) was 183 km/h at Mokohinau Island on 11 May in strong easterly conditions, and also 183 km/h at Hicks Bay on 18 June.
  • The driest rainfall recording locations were Alexandra in Central Otago with 376mm of rain for the year, followed by Clyde with 378 mm, and then Middlemarch with 386 mm.
  • Of the regularly reporting gauges, Cropp River in the Hokitika River catchment recorded the highest rainfall with 10,940 mm, followed by North Egmont 8878 mm for 2008.
  • Wellington was by far the wettest main centre with 1662 mm, in contrast Christchurch and Dunedin were the driest of the five main centres with a mere 704 and 705 mm respectively. Auckland received 1226 mm and Hamilton 1220 mm. Blenheim was the sunniest centre in 2008, recording 2505 hours, followed by Nelson with 2472 hours, then Lake Tekapo with 2444 hours. Christchurch was the sunniest of the five main centres with 2230 sunshine hours, then Wellington 2205 hours. Auckland recorded 2108 hours, Hamilton 2057 hours and Dunedin 1912 hours.

Prevailing climate patterns –  A rollercoaster. From La Niña to neutral and back again.

Overall, mean sea level pressures were near average over New Zealand, with more anticyclones (‘highs’) than average to the east of the country.  This gave more frequent winds from the north and north east over the country. Warmer than normal sea temperatures prevailed around New Zealand from January to May, disappearing over winter, and becoming cooler during late spring before warming up again by early summer.

A moderate La Niña occurred in the equatorial Pacific from January to April, with neutral conditions becoming established over winter. However a weak-moderate La Niña had redeveloped by December.

Over New Zealand, monthly wind-flow patterns were highly variable throughout the year:

  • January: very dry and settled conditions
  • February: unsettled, with low pressures
  • March: dry and settled (much like January)
  • April: warm, moist northeasterlies affected the North Island
  • May: wet and cold easterlies predominated
  • June: strong southwesterlies prevailed
  • July: unsettled, with low pressures
  • August: wintry southerlies occurred frequently
  • September: a switch to warmer northwesterlies
  • October: tending more westerly
  • November: back to warm, northwesterlies (similar to September)
  • December: moist northeasterlies.

2008 temperatures: Above average especially in west of the North Island

The national average temperature in 2008 was 12.9 °C, 0.3 °C above the 1971–2000 normal.  This was a result of several warm months and only one cold month. Temperatures were between 0.5 and 1.0°C above average in the west of the North Island and Nelson and up to 0.5 °C above average in most other regions. The warmest location was Leigh, with a mean temperature for the year of 16.5°C (0.3 °C above normal). For New Zealand as a whole, five were warmer than average months (January–March, June, and September); one month was cooler than average (May). All other months had mean temperatures close to the climatological average.

Hawera and Cromwell recorded their 2nd warmest years on record (based on averaging the mean daily temperature).

Wanganui and Cromwell recorded their highest average maximum temperature on record (based on averaging the maximum temperature recorded each day).

Near or record high annual average temperatures for 2008:

Location Mean temperature (°C) Departure (°C) Year Records began Comments
Mean Temperature
Kaikohe AWS 15.3 0.7 1973 3rd highest
Paeroa AWS 15.2 0.6 1947 3rd highest
Tauranga Aero AWS 15.4 0.8 1913 3rd highest
Port Taharoa Aws 15.6 0.5 1973 3rd highest
Te Kuiti EWS 14.2 0.6 1959 4th highest
Paraparaumu Aero 13.7 0.7 1953 3rd highest
Hawera AWS 13.1 0.6 1977 2nd highest
Ohakune EWS 10.9 0.7 1962 3rd highest
Wanganui,Spriggens Park 14.5 0.6 1937 4th highest
Lake Rotoiti EWS 9.8 0.7 1965 3rd highest
Nelson AWS 13.4 0.5 1943 4th highest
Arthurs Pass 8.2 0.6 1978 4th highest
Cromwell EWS 11.7 0.9 1949 2nd highest
Mean Maximum Temperature
Whangaparaoa AWS 19.0 1.0 1982 2nd highest
Port Taharoa AWS 19.4 0.8 1973 3rd highest
Te Kuiti EWS 19.7 0.9 1959 2nd highest
New Plymouth AWS 18.3 0.9 1944 3rd highest
Waipawa EWS 18.8 0.8 1945 2nd highest
Wallaceville EWS 17.9 1.0 1939 3rd highest
Hawera AWS 17.1 0.5 1977 3rd highest
Ohakune EWS 16.0 1.0 1962 3rd highest
Wanganui,Spriggens Park 18.7 0.9 1937 Highest
Lake Rotoiti EWS 15.7 1.2 1965 2nd highest
Milford Sound AWS 15.7 1.1 1934 3rd highest
Nelson AWS 18.2 0.9 1943 2nd highest
Hanmer Forest EWS 17.9 1.3 1906 4th highest
Arthurs Pass 12.7 0.7 1978 3rd highest
Le Bons Bay AWS 14.8 0.3 1984 3rd highest
Dunedin Aero AWS 16.4 0.6 1947 2nd highest
Cromwell EWS 17.9 1.2 1949 Highest
Mean Minimum Temperature
Kaitaia EWS 12.2 0.4 1967 4th highest
Kaikohe AWS 11.8 0.7 1973 2nd highest
Tiri Tiri Lighthouse 13.7 1.0 1982 2nd highest
Arc Kumeu EWS 10.2 0.7 1978 Highest
Whitianga Aero AWS 10.8 1.0 1962 2nd highest
Paeroa AWS 10.4 0.9 1947 3rd highest
Hawera AWS 9.1 0.7 1977 3rd highest
Cape Campbell AWS 10.8 1.5 1953 4th highest
Darfield EWS 6.9 0.7 1939 4th highest
Gore AWS 5.6 0.2 1971 3rd highest

New records for temperature extremes were set during the January 2008 heat wave, with extremely high day and night time temperatures especially in the west of the North Island.

Near or record high or low annual temperature extremes for 2008:

Location Value (°C) Date of occurrence Year Records began Comments
Highest extreme maximums
New Plymouth AWS 30.2 20 Jan 1944 2nd highest
Castlepoint AWS 30.9 22 Jan 1972 3rd highest
Palmerston North EWS 31.2 22 Jan 1918 4th highest
Wallaceville EWS 30.9 21 Jan 1939 Highest
Stratford EWS 27.7 21 Jan 1960 Equal 4th highest
Hawera AWS 26.4 21 Jan 1977 Equal 4th highest
Highest extreme minimums
Rotorua Aero AWS 19.8 22 Jan 1972 3rd highest
Taupo AWS 20.2 22 Jan 1950 Highest
Hamilton AWS 22.2 22 Jan 1946 Highest
Turangi 2 EWS 20.0 22 Jan 1968 Highest
Paraparaumu Aero AWS 20.3 22 Jan 1972 2nd highest
Wallaceville EWS 19.2 22 Jan 1972 Equal 4th highest
Stratford EWS 20.3 22 Jan 1972 Highest
Waiouru AWS 18.5 22 Jan 1972 Highest
Wanganui,Spriggens Park 21.7 22 Jan 1972 2nd highest
Takaka EWS 18.8 22 Jan 1978 4th highest
Reefton EWS 17.8 8 Jan 1972 4th highest
Nelson Aero 20.5 22 Jan 1943 2nd highest
Lowest extreme maximums
Castlepoint AWS 6.5 9 Aug 1972 Lowest
Hokitika Aero 6.0 15 Aug 1964 Equal 3rd lowest
Arthurs Pass EWS 0.3 15 Aug 1973 Equal 2nd lowest
Lowest extreme minimums
New Plymouth AWS -2.0 7 Jul 1944 4th lowest
Martinborough EWS -4.0 21 Aug 1986 Equal lowest
Waiouru AWS -9.1 7 Aug 1962 2nd lowest
Blenheim Aero AWS -6.1 19 Aug 1932 2nd lowest
Arthurs Pass EWS -9.5 20 Aug 1973 Equal 2nd lowest

A very sunny year, especially in Hawke’s Bay, and the south of the South Island

It was a sunny year everywhere, with nowhere in New Zealand recording below normal sunshine totals. Sunshine hours were more than 115 percent of normal in central areas of the North Island, Hawke’s Bay, south Canterbury, coastal Southland and eastern Otago. Turangi, Dannevirke, Waipawa, and Invercargill experienced their sunniest years on record. All other regions recorded between 105 and 110 percent of normal except in those areas exposed to the north east: Northland, coastal Bay of Plenty, Buller, Nelson, and Marlborough. The sunniest centre in 2008 was Blenheim, recording 2505 hours, followed by Nelson with 2472 hours, then Lake Tekapo with 2444 hours.

Near or record high sunshine hours for the year 2008:

Location 2008 Sunshine (hours) Percent of normal Records Began Comments
Turangi 2 EWS 2186 113 1976 Highest
Dannevirke EWS 2080 116 1963 Highest
Waipawa EWS 2327 123 1945 Highest
Dunedin, Musselburgh EWS 1912 119 1947 3rd highest
Cromwell EWS 2399 115 1979 2nd highest
Balclutha 2096 128 1964 2nd highest
Invercargill Airport 1907 119 1935 Highest

Rainfall:

Above normal in the Far North, Marlborough and north Canterbury;
Normal throughout much of New Zealand;
Below normal in Gisborne, Hawke’s Bay and Fiordland

2008 annual rainfall was close to normal in many areas of New Zealand. Annual rainfall was more than 135 percent of normal at Cape Reinga, Wellington and in central Marlborough, and more than 120 percent of normal in the Far North, Marlborough, the Kaikoura Coast and north Canterbury. Above normal rainfall (at least 110 percent of normal) occurred in the remainder of north and central Canterbury, and other areas exposed to the north east in Northland and Nelson. Annual rainfall was less than 90 percent of normal in the south west of the South Island, and the east of the North Island, with parts of Fiordland, eastern Otago and southern Hawke’s Bay recording less than 80 percent of normal.

Extremely high and low annual rainfall, for the year 2008:

Location 2008 rainfall (hours) Percentage of normal Year Records Began Comments
Warkworth EWS 1750 119 1966 2nd highest
Kelburn, Wellington 1662 135 1864 3rd highest
Blenheim Aero AWS 994 134 1927 2nd highest
Blenheim EWS 803 135 1930 Well above average
Waipawa EWS 611 73 1945 2nd lowest
Lake Rotoiti EWS 1281 80 1933 2nd lowest

Of the regularly reporting gauges monitored by NIWA, Cropp River in the Hokitika River catchment recorded the highest rainfall with 10,940 mm, followed by North Egmont with 8878 mm for 2008. Alexandra in Central Otago, was the driest of the sites where NIWA records rainfall, with 376 mm (102% of normal), followed by Clyde with 378 mm (91% of normal) and Middlemarch with 386 mm (76 percent of normal).

Of the five main centres, Wellington was by far the wettest main centre with 1662 mm (135 percent of normal) followed by Auckland with 1226 (104 percent of normal) and Hamilton (1220 mm: 113 percent of normal). In contrast, Christchurch and Dunedin were the driest of the five main centres with a mere 704 (112 percent of normal) and 705 mm (88 percent of normal) respectively. Near record values of annual 1-day rainfall extremes occurred at a few localities.

One day rainfall extremes for 2008:

Location 2008 1-day extreme rainfall (mm) Date Year Records Began Comments
Kaikohe AWS 130 22 Feb 1956 4th highest
Taupo AWS 101 15 Apr 1949 3rd highest
Nelson Aero 105 14 Apr 1941 4th highest
Hanmer Forest EWS 135 25 Aug 1905 3rd highest

2008 climate in the five main centres

Auckland was the warmest of the five main centres. Wellington was by far the wettest. Christchurch and Dunedin were the driest. Christchurch was the sunniest.

Rainfall was the 3rd highest on record in Wellington, in records that go back to 1864. It was also wetter than normal in Hamilton and Christchurch, but drier than normal in Dunedin. It was especially sunny in Dunedin, which recorded the 3rd sunniest year (records go back to 1947). Sunshine totals were above average in most other main centres. Temperatures were above average in Hamilton, Wellington and Dunedin.

Location 2008 Mean temp.(°C) Dep. from normal (°C)
2008 rainfall (mm) % of normal
2008 Sunshine (hours) % of normal
Auckland 15.4 +0.1 Normal 1226a 102 Normal 2108 105 Above normal
Hamilton 14.0 +0.3 Above normal 1220 113 Above normal 2057 100 Near normal
Wellington 13.5 +0.7 Above normal 1662 135 3rd highest 2201 107 Above normal
Christchurch 11.6 +0.0 Normal 704 114 Above normal 2234b 106 Above normal
Dunedin 11.3 +0.3 Above normal 705 88 Below normal 1912 135 3rd highest

a Owairaka  b Christchurch Airport

Significant extremes

Drought

By 29th March severe soil moisture deficits (more than 130 mm) were present in parts of Auckland, Waikato, South Taranaki, Manawatu, Wairarapa and Marlborough. Significant soil moisture deficits (more than 110 mm) persisted throughout much of the west of the North Island, and from the Heretaunga Plains to Wairarapa, and in the east of the South Island. The combination of the hot and dry conditions meant that dairy farmers continued drying off dairy stock, with sheep farmers selling stock early. The stock feed situation remained very low in the drought areas. April rainfall ended the severe and significant soil moisture deficits in much of the North Island, and May rains brought relief in other areas. This drought dramatically affected production from pastoral agriculture in the west of the North Islands, with economic costs estimated of at least $1 billion, and MAF reporting an eleven percent fall in sheep numbers due to the drought.

Floods

There were numerous heavy rainfall events during 2008, about eighteen of which produced floods. The worst flooding events during 2008 were those of 14–16 April in the Central North Island, 29–30 July in Marlborough, and 26 August in Marlborough/North Canterbury. During the first event, heavy rainfall and flooding in Northland, Bay of Plenty, Central North Island and Nelson resulted in 8 deaths, one from a lightning strike, and seven in a flash flood. The deluge caused flooding of some homes in Rotorua and car crashes, with a two metre high wall of water sweeping down an Otonga hillside. The heavy rainfall in July resulted in a state of emergency being declared in Marlborough due to extensive surface flooding. The storm knocked out an important water pipeline in Nelson. Picton police and volunteers sandbagged the waterfront in an effort to save the town from flooding. The cost of the storm on the country was estimated to be more than $10 million. Two people drowned while attempting to cross a swollen stream near Kawakawa in Northland. On 26 August slips closed SH1 from Weld Pass, near Seddon, to Cheviot, and roads around Kaikoura were sandbagged after surface flooding and the main water pipe into Cheviot was broken cutting water supply to the town. Mason River, a tributary of the Waiau River, burst its banks, putting the road under 4 m of water and isolating several houses. A raging Eyre River in north Canterbury claimed up to 100 dairy cows when a bridge approach was washed away and the settlement of Peketa, south of Kaikoura, was evacuated after the Kahutara River burst its banks.

Snow

There were seven moderate snowfall events over the winter season, with North Island ski areas reported good snowfall. Particularly notable were the snowfall on 15–17 August and the spring snowstorms. On the 15th – 17th of August a deep low brought heavy snow to the Southern Alps and the western and north western ranges. Arthur’s Pass received about 1m of snow, closing the road for 3 days, while Mt Cook Village received about 60cm. This storm was particularly unique as snow fell to low levels (~100m) on the western and north western side of the Southern Alps. Areas not usually associated with heavy snow falls (e.g. Nelson Ranges and behind Buller) were also affected. On 27 September, snow fell to about 220 m in Otago and Southland. Cyclists on the Otago Central Rail Trail had to be picked up after being caught in a short but vicious storm which dumped 12 cm of snow at Wedderburn in just a couple of hours. SH 8 through the Lindis Pass was also closed briefly during the height of the snowstorm when a truck and trailer jack-knifed near the pass summit in the treacherous conditions. On 5 November an unseasonably cold blast hit the South Island, blanketing inland Southland, Fiordland and Central Otago with snow and hail. The brutal conditions forced Tour of Southland organisers to shorten two stages of the race, as competitors faced temperatures as low as 1 °C. Locals say it is the first time since the 1970s that they have seen this much snow in November.

Wind

Strong wind events were particularly marked in September and October, when rather boisterous conditions occurred at times. On 23 September high winds averaging 70 km/hr and gusting up to 100 km/hr disrupted flights at Dunedin Airport between noon and 5.30pm. Winds gusts reached 140 km/hr at Swampy Summit above Dunedin, 100 km/hr at Taiaroa Head, 135 km/hr on the Rock and Pillar Range, near Middlemarch. Some trees were damaged around the region. Nine flights were cancelled at Queenstown Airport because of poor visibility, strong winds and driving rain. High winds, with gusts of up to 157 km/hr, forced the closure of the Remarkables Ski Field at 2pm. On 7 October extreme winds caused significant disruption in the upper and lower North Island, forcing road closures and damaging property and trees. Wind speeds of up to 130 km/hr were recorded in Wellington, and up to 160 km/hr in some of the surrounding hills. High winds even moved large shipping containers on Wellington's waterfront. Wellington Airport was closed for 6 hours, with flights resuming in the afternoon. Power was cut to about 4000 households and businesses in the Wairarapa and Wellington region as a result of trees falling over power-lines. A mini tornado ripped through the Cambridge area about 3.00am on 17 October. About 100 homes were affected, with 12 residents evacuated from one wing of a rest home. Trees and power-lines were brought down, and an 80-year-old oak tree was just plucked out of the ground.

Full report

Climate Summary for 2008 (PDF 233 KB)

For further information, please contact:

Dr James Renwick, NIWA Principal Scientist, Climate Variability & Change
Phone +64 4 386 0343
Mobile +64 21 178 5550
j.renwick@niwa.co.nz

Dr Andrew Tait, Climate Scientist, NIWA National Climate Centre
Phone +64 4 386 0562
Mobile +64 27 327 7948
a.tait@niwa.co.nz

Acknowledgement of NIWA as the source is required.