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

 New Zealand national climate summary – the year 2008. 

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:

 

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:

 

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:

 

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:

 

 

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:

 

 

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.