Climate Summary – April 2007 Dry, sunny, cool

NATIONAL CLIMATE CENTRE TUESDAY 1 MAY 2007

National Climate Summary – April 2007 Dry, sunny and cool

* Rainfall: Below normal in most regions
* Soil moisture: Significant deficits persist in Hawke’s Bay, central Marlborough, parts of eastern Canterbury and Central Otago
* Temperature: Below normal over much of the North Island
* Sunshine: Above average in many areas

April was a relatively dry month overall, especially over the North Island and the north and west of the South Island. It was an autumn like month, with anticyclones to the west and winds from the southerly sector producing cooler than normal conditions for many and plentiful sunshine with the dryness. Less than 50 percent (half) the normal rainfall was recorded in eastern parts of Northland, Taranaki, Gisborne, Horowhenua, and much of the west of the South Island. Rainfall at the end of the month meant significant soil moisture deficits (at least 110 mm) persisted only in Hawke’s Bay, central Marlborough parts of eastern Canterbury and Central Otago. Temperatures were at least 0.5°C below average in many North Island areas, but near normal over much of the South Island. The national average temperature was 13.0°C, 0.5° below normal. April was a sunny month in many regions, apart from the south and east of the South Island, with record high April sunshine hours recorded at Kaitaia. Anticylones (‘highs’) were more very much frequent to the south of Tasmania, with depressions (‘lows’) often south of the Chatham Islands, resulting in more frequent southerlies than usual over New Zealand.

Other Highlights:

- The highest temperature during April 2007 was 26.6 °C recorded at Hastings on the 1st. The lowest air temperature during the month was -3.1 °C recorded at Tara Hills, Omarama on the 12th, and also at Ranfurly on the 30th.

- High rainfall events, with at least 75 mm in 24 hours affecting Fiordland on the 10th and 23rd of April.

- Southwest gales with very high gusts, exceeding 130 km/h, were measured in parts of Auckland between the 12th and 13th of April, the highest being 146 km/h at North Shore on the 13th.

- Auckland was the warmest and sunniest, and Dunedin the driest, of the five main centres. Rainfall was near normal in Wellington and Christchurch, and below normal in the other main centres. Temperatures were near normal in Auckland and below normal in the other main centres. Sunshine hours were above normal in Auckland and Wellington, near normal in Hamilton and Christchurch, and below normal in Dunedin.

Rainfall: Rainfall was 50 percent (half) or less of normal in eastern parts of Northland, Taranaki, Gisborne, Horowhenua, and much of the west of the South Island. Rainfall was less than 75 percent (three quarters) of normal in many other regions.
Temperature: Mean temperatures were at least 0.5 °C below average throughout much of the North Island, about 1.0 °C below average in parts of Hawke’s Bay, Wairarapa, and Manawatu, and near average over much of the South Island.
Sunshine: April sunshine hours and/or solar radiation were more than 110 percent of normal in many areas of New Zealand, except South Taranaki, Manawatu, and the east of the South Island from Southland to the Canterbury coast where they were near normal.

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RAINFALL: BELOW NORMAL IN MOST REGIONS

Rainfall was 50 percent (half) or less of normal in eastern parts of Northland, Taranaki, Gisborne, Horowhenua, and much of the west of the South Island. Rainfall was less than 75 percent (three quarters) of normal in many other regions. Rainfall was near normal in western areas of Northland and Auckland, as well as Wanganui, and North Canterbury.

Near record low April rainfall was recorded at:

Location / April Rainfall (mm) / Percentage of normal / Year Records began / Comments
Franz Josef / 120 / 28 / 1983 / 3rd lowest
Lauder / 16 / 36 / 1987 / 2nd lowest

TEMPERATURE: BELOW NORMAL OVER MUCH OF THE NORTH ISLAND

Overall mean temperatures were slightly below average throughout much of New Zealand. However, they were at least 0.5 °C below average throughout much of the North Island, about 1.0 °C below average in parts of Hawke’s Bay, Wairarapa, and Manawatu, and near average over much of the South Island. The national average temperature was 13.0°C (0.5°C below normal).

SUNSHINE: ABOVE AVERAGE IN MANY AREAS

April sunshine hours and/or solar radiation were more than 110 percent of normal in many coastal areas of the North Island and the west of the South Island. Sunshine hours were near normal in South Taranaki, Manawatu, and on the Canterbury coast, and below normal in Southland and Otago.

Near record high April sunshine hours were recorded at:

Location / April Sunshine (hrs) / Percentage of normal / Year Records began / Comments
Kaitaia Observatory / 198 / 124 / 1986 / Equal highest
New Plymouth Airport / 220 / 127 / 1905 / 3rd highest
Lake Tekapo / 212 / 133 / 1928 / 3rd highest

APRIL’S CLIMATE IN THE FIVE MAIN CENTRES

Auckland was the warmest and sunniest, and Dunedin the driest, of the five main centres. Rainfall was near normal in Wellington and Christchurch, and below normal in the other main centres. Temperatures were near normal in Auckland and below normal in the other main centres. Sunshine hours were above normal in Auckland and Wellington, near normal in Hamilton and Christchurch, and below normal in Dunedin.

April 2007 main centre climate statistics:

Location / Apr. Mean Temp. (°C) / Dep. from normal (°C) / / Apr. rainfall (mm) / % of Normal / / Apr. Sunshine (hours) / % of Normal /
Auckland / 16.1 / -0.2 / Normal / 66a / 62 / Below normal / 187 / 119 / Above normal
Hamilton / 14.0 / -0.5 / Below normal / 59 / 63 / below normal / 160 / 98 / Near Normal
Wellington / 13.1 / -0.7 / Below normal / 92b / 92 / Near normal / 174 / 112 / Above normal
Christchurch c / 11.4 / -0.7 / Below Normal / 56 / 109 / Near normal / 166 / 103 / Near normal
Dunedin / 11.1 / -0.8 / Below normal / 36 / 62 / Below normal / 106 / 87 / Below Normal
a Owairaka b Wellington Airport c Christchurch Airport

HIGHLIGHTS AND EXTREME EVENTS

* Temperature
The highest temperature during April 2007 was 26.6 °C recorded at Hastings on the 1st. The lowest air temperature during the month was -3.1 °C recorded at Tara Hills, Omarama on the 12th, and also at Ranfurly on the 30th.

* High rainfall
There were only a couple of high rainfall events, with at least 75 mm in 24 hours. These were:

Date / Region / Location / Rainfall (mm)* / Other comments
10 Apr. / Fiordland / Milford Sound / 210 /
23 Apr. / Fiordland / Milford Sound / 84 /
*(9am-9am) rainfall

* High winds
Southwest gales with very high gusts, exceeding 130 km/h, were measured in parts of Auckland between the 12th and 13th of April, the highest being 146 km/h at North Shore on the 13th.

ENDS

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