The Climate in April

 

NATIONAL CLIMATE CENTRE                   Monday 3 May 2010

     

National Climate Summary-April 2010: North Island continues dry, sopping wet in southwest.  

• Rainfall: Continued dry across much of the North Island, Marlborough, and Canterbury.  Extraordinarily wet in the southwest of the South Island. 
• Soil moisture:  Significant deficits continue in many areas of the North Island, as well as Marlborough and Canterbury, even after helpful rain at the end of April.
• Temperature:  Very warm in many regions of the South Island, as well as eastern Northland and Auckland, Coromandel and the Wairarapa. Near average temperatures elsewhere. 
• Sunshine: Extremely sunny for the east coast of the North Island and Northland.  Very cloudy in the west and south of the South Island.

 

More frequent anticyclones (‘highs’) were located over and to the east of the North Island during April, resulting in a very dry month for much of the North Island and upper South Island. Drought was declared for Auckland, Waikato, Bay of Plenty, South Taranaki, South Canterbury and Otago in April, joining Northland which was declared a drought area in January. Even after some helpful rainfall at the end of the month, significant soil moisture deficits remain in many areas of the North Island (except for Taranaki, Gisborne, and the Kapiti Coast), as well as in Marlborough and Canterbury. In contrast, enhanced northwest winds affected the South Island, producing extraordinarily high rainfall in the southwest of the South Island.  

Well below normal April rainfall (less than 50 percent of normal) occurred across most of the North Island, as well as in Nelson, Marlborough and north Canterbury. Areas that received slightly more substantial rainfalls (between 50 and 80 percent of normal) included Taranaki, Gisborne, the Kapiti Coast, and south Canterbury. In comparison, it was an extraordinarily wet April in Fiordland, south Westland and parts of Southland, with more than double normal rainfall experienced there.  Rainfall was also above normal (more than 120 percent of usual) in Otago, but near normal in north Westland and Buller.  

It was an extremely warm April for much of the South Island, the Wairarapa, eastern Northland and eastern Auckland, with temperatures more than 1.2°C above average.  In contrast, April temperatures were near average across the remainder of the North Island (within 0.5°C of the long-term average), as well as in Buller.  The New Zealand national average temperature was 14.2°C (+0.8°C above the long-term April average). 

April was an extremely sunny month for the eastern North Island and Northland, with totals above 125 percent of normal. It was also rather sunny (between 110 and 125 percent of normal) in the Central Plateau, Bay of Plenty, Manawatu-Wanganui, Wellington, Marlborough and Canterbury.  It was a cloudy month for the West Coast, Southland and Otago, with below average sunshine (between 75 and 90 percent of normal).  

Further Highlights:

• The highest April temperature was 28.6°C, recorded at Darfield on the 1st.
• The lowest April temperature was -3.1 °C, recorded at both Turangi and Hanmer on the 8th.
• The highest April 1-day rainfall was 314 mm, recorded at Milford Sound on the 25th (the 2nd- highest daily value for April at this site).
• The highest wind gust was 152 km/hr, recorded at Cape Turnagain on the 15th.
• Of the six main centres, Auckland and Tauranga were equally the warmest, Dunedin was the coolest, Christchurch was the driest, Auckland the wettest, and Tauranga the sunniest.

 

 

For further information, please contact:

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

Tel.  (09) 375 4506 (work)

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

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

Rainfall: continued dry across much of the north island, as well as marlborough and canterbury.  extraordinarily wet in the southwest of the country. 

Well below normal April rainfall (less than 50 percent of normal) occurred across most of the North Island, as well as in Nelson, Marlborough and north Canterbury. It was the driest April on record for Masterton and Culverden. Areas that received slightly more substantial rainfalls (between 50 and 80 percent of normal) included Taranaki, Gisborne, the Kapiti Coast, and south Canterbury. Drought was declared for Auckland, Waikato, Bay of Plenty, South Taranaki, South Canterbury and Otago in April, joining Northland which was declared a drought area in January. Even after some helpful rainfall at the end of the month, significant soil moisture deficits remain in many areas of the North Island (except for Taranaki, Gisborne, and the Kapiti Coast), as well as in Marlborough and Canterbury.   

In comparison, it was an extraordinarily wet April in Fiordland, south Westland and parts of Southland, with more than double normal rainfall experienced there.  Rainfall was also above normal (more than 120 percent of usual) in Otago, but near normal in north Westland and Buller.  It was the wettest April on record for Milford Sound and Manapouri.   

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

 

 

TEMPERATURES: very warm in the south island, eastern northland and auckland, coromandel and the wairarapa.  near average temperatures elsewhere. 

It was an extremely warm April for much of the South Island, the Wairarapa, eastern Northland and eastern Auckland, with temperatures more than 1.2°C above average.  In contrast, April temperatures were near average across most of the North Island (within 0.5°C of the long-term average), as well as in Buller.  The New Zealand national average temperature was 14.2°C (+0.8°C above the long-term April average)1. 

April minimum temperatures were the highest on record at Whangaparaoa, Ngawi, Takaka, Nelson, Blenheim, Le Bons Bay and Cromwell.  April maximum temperatures were the highest on record for Arthurs Pass and Alexandra. 

Record or near-record April mean maximum daily air temperatures were recorded at: 

 

 

Record or near-record April mean minimum daily air temperatures were recorded at: 

 
 

 

SUNShine:  extremely SUNNY in the east of the north island and northland, very cloudy in the southwest 

April was an extremely sunny month for the eastern North Island and Northland, with totals above 125 percent of normal. It was the sunniest April on record for Martinborough, in records that began in 1986. It was also rather sunny (between 110 and 125 percent of normal) in the Central Plateau, Bay of Plenty, Manawatu-Wanganui, Wellington, Marlborough and Canterbury.  It was a cloudy month for the West Coast, Southland and Otago, with below average sunshine (between 75 and 90 percent of normal).  

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

 

 

APRIL CLIMATE IN THE SIX MAIN CENTRES  

Of the six main centres, Auckland and Tauranga were equally the warmest, Dunedin was the coolest, Christchurch was the driest, Auckland the wettest, and Tauranga the sunniest.   

It was a warm April for all of the main centres, except Auckland (where temperatures were close to average).  It was a dry month for all of the main centres, except Dunedin (which recorded near normal April rainfall).  Sunshine totals in all of the main centres were near to April normal, except Tauranga (which experienced above normal sunshine hours).   

April 2010 main centre climate statistics:  

a Mangere      b Tauranga Airport   c Hamilton Airport     d Kelburn     e Christchurch Airport    f Musselburgh  g Ruakura   
 

HIGHLIGHTS AND EXTREME EVENTS 

• Heavy rain and flooding

 

 

The highest 1-day rainfall in April was 314 mm, recorded at Milford Sound on the 25th (the 2nd-highest daily value for April at this site). Several other sites in the southwest of the country also broke April 1-day rainfall records on the 25th, namely Manapouri, Queenstown, and Lumsden. 

Heavy rain on 25 April caused flooding on the road to Milford Sound, stranding visitors.  

On 26 April, flooding closed SH94 from Milford Sound to Te Anau, and from Te Anau east to Mossburn. SH97 was closed between Five Rivers and Mossburn, and SH6 between Kingston and Athol was affected by surface water. About 120 trampers were evacuated by helicopter from the Milford Track. Te Anau residents were without telephone links after flooding cut the main fibre optic cable at Whitestone Bridge at about 1.30 pm. An alternative radio link was set up about 7.30 pm. Mobile phone sites were also affected. A property in Lowther Rd, about 12 km north of Lumsden, was evacuated when floodwater flowed through the house. Fences on the property were also underwater. The Dart River breached its banks, flooding Kinloch Road, which was closed by the Queenstown Lakes District Council.  

On 27 April, SH99 was closed between Underwood and Wallacetown. Thousands of hectares of farmland were under water after rivers overflowed, with many stock isolated on patches of higher ground. In Tuatapere, the Waiau River burst its banks flooding the Domain, and sending 950 mm of water through the rugby clubrooms. The domestic water supply and all electronic communication ceased at 1.33 am. Water supplies were re-instated about 8.45 am, but residents were asked to conserve water, and boil drinking water. On the Milford and Routeburn Tracks, several bridges were washed away, and there were many slips and washouts, causing DoC to close the tracks. Access roads into Mt Aspiring National Park were also damaged. 

On 29 April, the high levels of Lake Wakatipu caused some roads and reserves on the Queenstown foreshore to be flooded, mainly due to wind-blown waves.  At 8am on 30 April, Lake Wakatipu had risen to its "threshold" level where water overflowed on to foreshore streets and parks, but major flooding such as seen in 1999 was largely avoided because of flood protection measures. 

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

 

 

• Temperature

 

 

The highest April temperature was 28.6°C, recorded at Darfield on the 1st, the 4th-highest April temperature recorded in this area since records began in 1939. 

Record or near-record daily maximum air temperatures were recorded at:  

 

 

The lowest April temperature was -3.1 °C, recorded at both Turangi and Hanmer on the 8th.  The Turangi temperature was the equal-lowest April minimum temperature recorded in the area since records began in 1968.  In contrast, the highest April minimum temperatures were experienced in Hanmer Forest and Waipara West on the 26th, and Alexandra on the 13th, both associated with northwesterly winds drying and warming as they traverse the Southern Alps.  

Record or near-record daily minimum air temperatures were recorded at:  

 

 

• High winds

 

 

The highest wind gust in April was 152 km/hr, recorded at Cape Turnagain on the 15th (not a record).   

Near-record high extreme wind gusts for April were recorded at: