National Climate Summary October 2009: Coldest October in over half a century

 

• Temperature:  The coldest October in 64 years, with all-time record low October temperatures in many areas. Exceptionally late snowfalls. Record low October temperatures were recorded on the 4th/5th in most North Island locations, and on the 9th at many South Island sites.
• Rainfall: Well above normal rainfall in the east of the North Island, as well as in Wellington, Marlborough and parts of Canterbury.  Very dry on the West Coast of the South Island.
• Sunshine: Extremely sunny on the West Coast of the South Island. 

 

Record or near-record low October temperatures were experienced in many locations, with temperatures more than 2.0°C below average throughout eastern and alpine areas of the South Island, as well as in the lower half of the North Island. Temperatures were below average (between 0.5°C and 1.2°C below average) elsewhere.  Overall for New Zealand, it was the coldest October in 64 years (since 1945), with a national average temperature of 10.6°C (1.4°C below the long-term October average). Such a cold October has occurred only four times in the past 100 years. Record low October temperatures were recorded on the 4th/5th in most North Island locations, and on the 9th at many South Island sites. 

Well above normal October rainfall (above 150 percent of normal) was experienced across the East Coast of the North Island, as well as Wellington, Marlborough and Canterbury (north of about Ashburton).  Rainfall was near-record (and more than 200 percent of normal) in parts of Hawkes Bay, Gisborne and the Tararua District.  Rainfall was also above normal (between 120 and 150 percent of normal) in Manawatu-Wanganui, Waikato and the Bay of Plenty.  Rainfall totals were near normal (between 80 and 120 percent of normal) in the Tasman District, central Otago, Auckland, Taranaki and western parts of Northland. In contrast, it was very dry on the West Coast and in Fiordland, with only about half of normal October rainfall recorded there.   

October sunshine totals were well above normal (more than 125 percent of normal) on the West Coast and in Fiordland; in contrast, sunshine totals were below normal (between 75 and 90 percent of normal) for Taranaki, Wellington and the Wairarapa. Elsewhere, sunshine totals were in the near normal range.   

Unseasonable snowfalls characterised October 2009. An exceptionally heavy snow event on the 4th/5th in the Hawkes Bay and Central North Island was estimated to be the worst in October since 1967, stranding hundreds of travellers, closing roads, and resulting in heavy lambing losses. Many locations in the North Island experienced record low October temperatures on the 5th.  Snowfall was also observed in Taranaki, Waikato and Rotorua on the 6th, for the first time in about 30 years around Rotorua. Snowfall also affected Otago and Canterbury on the 8th/9th, with many sites observing record low October temperatures on the 9th.       

During October 2009, lower than normal pressures and frequent southeasterly winds affected New Zealand, leading to the low temperatures around the country. Southeasterlies also led to the sunny and dry conditions experienced on the west coast of the South Island, as the Southern Alps provided shelter from the wind.  

Further Highlights:

• The highest temperature was 24.3°C recorded at Whangarei on the 17th (4th highest in October). The lowest temperature of -5.5 °C was recorded at Ranfurly on the 5th (not a record).
• The highest 1-day rainfall was 89 mm, recorded at Motu, Gisborne, on the 4th (not a record).
• The highest wind gust was 148 km/hr, recorded at Stewart Island on the 21st (not a record).
• Of the six main centres, Tauranga was the warmest, Wellington the wettest, Dunedin the coolest and driest, and Christchurch the sunniest. 

 

For further information, please contact:

Ms Georgina Griffiths – Climate Scientist– NIWA National Climate Centre, Auckland,

Tel. (09) 375 4506 (work) or (027) 2936545 (mobile); or

Dr Andrew Tait – Climate Scientist – NIWA National Climate Centre, Wellington,

Tel.  (04) 386 0562 (work) or (027) 327 7948 (mobile)  

TEMPERATURES: COLDEST OCTOBER IN 64 YEARS; RECORD OR NEAR RECORD COLD IN MANY LOCATIONS  

Record or near-record low October temperatures were experienced in many locations, with temperatures more than 2.0°C below average throughout eastern and alpine areas of the South Island, as well as the lower half of the North Island. Temperatures were generally below average (between 0.5°C and 1.2°C below average) elsewhere.  It was the coldest October in 64 years (since 1945), with a national average temperature of 10.6°C (1.4°C below the long-term October average). Such a cold October has occurred only four times in the past 100 years.    Record low October temperatures were recorded on the 4th/5th in most North Island locations, and on the 9th at many South Island sites.  

Extreme low October mean maximum daily air temperatures were recorded at: 

 

Notably, the mean minimum temperature recorded at Queenstown (2.8°C) was the lowest ever for October, since records began in 1871. 

 

Extreme low October mean minimum daily air temperatures were recorded at: 

 
 

Rainfall: VERY WET IN THE EASTERN NORTH ISLAND, WELLINGTON, MARLBOROUGH, AND PARTS OF CANTERBURY.  VERY DRY on the west coast.  

Well above normal October rainfall (above 150 percent of normal) was experienced across the East Coast of the North Island, as well as Wellington, Marlborough and Canterbury (north of about Ashburton).  Rainfall was, in fact, more than 200 percent of normal in parts of Hawkes Bay, Gisborne and the Tararua District, with Dannevirke experiencing its wettest October since records began in 1951.  Much of the precipitation in these three regions fell on the 4th, during the significant snowfall event.  Rainfall was also above normal (between 120 and 150 percent of normal) in Manawatu-Wanganui, Waikato and the Bay of Plenty.  Rainfall totals were near normal (between 80 and 120 percent of normal) in the Tasman District, central Otago, Auckland, Taranaki and western parts of Northland. In contrast, it was very dry on the West Coast and Fiordland, with only about half of normal October rainfall recorded there.   

 

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

 

Sunshine:  very sunny ON THE WEST COAST; DULL in wellington, wairarapa, and TARANAKI 

October sunshine totals were well above normal (more than 125 percent of normal) on the West Coast and in Fiordland.  It was the second sunniest October at Greymouth in over 60 years, with a whopping 233 hours of bright sunshine. In contrast, sunshine totals were below normal (between 65 and 90 percent of normal) for Taranaki, Wellington and the Wairarapa. Elsewhere, sunshine totals were in the near normal range.   

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

 

OCTOBER CLIMATE IN THE SIX MAIN CENTRES  

October temperatures were the lowest on record for Wellington, Christchurch and Dunedin; were well below average in Auckland, below average in Hamilton, and near normal in Tauranga.  Monthly rainfalls were well above normal for all of the main centres except Dunedin (with below normal rainfall). Sunshine totals for October were near normal in all main centres except for Christchurch, which experienced 219 hours of bright sunshine in October. Of the six main centres, Tauranga was the warmest, Wellington the wettest, Dunedin the coolest and driest, and Christchurch the sunniest.   

October 2009 main centre climate statistics:  

a Mangere      b Tauranga Airport      c Kelburn     d Christchurch Airport    e Ruakura   
 

HIGHLIGHTS AND EXTREME EVENTS 

• Temperature

 

The highest temperature in October 2009 was 24.3°C recorded at Whangarei on the 17th (4th highest October temperature at this site).  

Record cold or near-record cold afternoon conditions were experienced on October 4th/5th in many North Island locations, associated with the heavy snowfall and bitterly cold southeast winds over the central North Island, as well as on the 9th at numerous southern sites, associated with another snowfall event in the southeast South Island.   

Extreme daily maximum air temperatures were recorded at:  

 

The lowest October temperature of -5.5 °C was recorded at Ranfurly on the 5th (not an October record). 

Extreme low daily minimum air temperatures were recorded at:  

 

• Heavy rain and flooding

 

The highest 1-day rainfall total for October was 89 mm, recorded at Motu (Gisborne) on the 4th (not an October record at this site). Other record or near-record 1-day rainfall totals for October are shown below.     

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

 

Heavy rain in Bay of Plenty on 5 October, caused slips in Tauranga, flooded businesses in Rotorua, and caused a 30 m high Acacia tree to fall, blocking the road at Pongakawa.  

Heavy rain in the early hours of 9 October caused surface flooding in Wellington, and closed the Johnsonville railway line.  

On 14 October, at 7.30 pm, a slip closed SH3 just north of New Plymouth. One lane was opened about 8 pm.  

Heavy rain in Wellington on 15-16 October caused surface flooding on SH1 north of the city, as well as causing slips in Lower Hutt and Evans Bay Parade. 

SH1 was closed by flooding near Marton, south of Wanganui, on 18 October. 

• High winds

 

The highest wind gust for October was 148 km/hr, recorded at Southwest Cape (Stewart Island) on the 21st (not an October record at this site).   

Gusty cross-winds forced the closure of New Plymouth airport for 20 hours from 3 pm on 4 October. The strong winds also brought down trees and cut the power supply to about 1000 properties in Taranaki, particularly Okato, Oakura, and Hawera. Power was also cut to about 1200 homes in Rotorua distict after high winds brought down trees. 

High winds on 5 October, together with the heavy snow, brought down trees and power poles in the central North Island, leaving about 1300 people without power. Some properties were without power for four days.  

Stock losses, particularly late born lambs, occurred in the Wairarapa during the first week in October, after several days of strong, very cold, southerly winds.  

Record high extreme wind gusts for October were recorded at:  

 

• Snow and ice

 

On 3 October, 20 cm of snow was reported to low levels in Fiordland and Southland. Coronet Peak skifield received 7 cm of fresh powder overnight on 2-3 October, while Treble Cone received 20 cm of snow, and Cardrona 15 cm.  

Overnight, 4-5 October, several hundred motorists were stranded in up to 50cm of snow along the Napier- Taupo Highway. Most were rescued by the army, but some spent the night in their vehicles. Snow was reported as far north as Te Aroha and Katikati, and on Mt Taranaki. Unexpected snow in the Motu-Matawai area, and further south at Te Pohue, caused significant losses in newborn lambs and calves.  

Roads closed by snow on 5 October were SH1 between Turangi and Taihape, SH5 from Taupo to Napier, SH38 in the Urewera National Park, SH47 at Turangi, SH49 from its junction with SH4 to Waiouru. The Desert Road, Napier-Taupo Road and SH38 remained closed until 7 October.  

On 6 October, Waikato residents woke to see snow on Mt Pirongia and Mt Te Aroha. A DoC ranger reported 15 cm of snow on the road up Mt Te Aroha, the heaviest fall since 1978. On Mt Taranaki, skiers could not reach the Manganui ski field because the access road was blocked by fallen trees. About 20-25 cm of snow covered the road. At North Egmont car park a car was trapped in snow, forcing the owner to spend the night in the hut. Snow was also reported in the Rotorua district, for the first time in about 30 years.  

Snow started falling in Central Otago in the evening on 8 October, and further north in Canterbury, it was reported in Darfield and Kirwee early in the morning of 9 October. Mt Hutt ski field received about 50 cm of new snow. 

• Hail

 

Hail was reported in central Wellington on 5 October, during the morning commute to work. 

Unseasonal, localised hail hit kiwifruit country around Tauranga and Te Puke several times in the last week of October, with heavy kiwifruit losses likely.