Jamie Morton

Jamie Morton is science reporter at the NZ Herald.

April 'abnormally warm' month for NZ

People enjoying the warm sunny weather in central Auckland. Photo / Martin Sykes
People enjoying the warm sunny weather in central Auckland. Photo / Martin Sykes

April was an "abnormally warm" month for many areas of the country, with much of the North Island experiencing mean temperatures well above average, a new report has found.

According to a climate report for April, released by the National Institute of Water and Atmosphere this morning, the nationwide average temperature last month was 14.5C - 1.1C above the recorded 1971-2000 April average.

Only a handful of areas on the North Island experienced "normal" conditions - within 0.5C of the April average - and no locations reported "below average" temperatures - 0.5C to 1.2C below the April average.

The South Island also experienced a warm April.

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But while well above average temperatures were common, especially for the west coast of the South Island, they were not as extensive for the island as a whole.

In terms of rainfall, April featured a much welcome change for many areas of New Zealand - mainly the North Island - with many areas in desperate need of rain receiving above normal or much above normal rainfall for the month.

This was echoed for a large part of the South Island, where in some areas, the wet wasn't so welcome.

As at the start of this month, soils in Tasman east through the Marlborough regions and south into much of Canterbury region were "abnormally wet" for this time of year and, for some areas, April rainfall was exceptional compared to normal, with three to five times the normal amounts falling.

But some regions of the North Island - particularly Northland and northern Auckland - soil moisture levels remained drier than normal at the start of the month, and more rain is needed.

The unusual conditions were driven by higher pressure than normal to the southeast of New Zealand. with lower than normal pressures over the Tasman Sea.

This pressure pattern resulted in north-easterly quarter wind flow anomalies for most parts of the country, with the exception of the north of the North Island, where lower pressures in the Tasman resulted in anomalous north-westerly airflows.

APRIL AT A GLANCE

Temperature: April was unusually warm for most of New Zealand, in particular the North Island, where well above average temperatures - greater than 1.2C above the April average - were recorded for the month.

Sunshine: Below normal sunshine (75-89 per cent of April normal amounts) to well below sunshine (less than 75 per cent of April normal) was recorded for the majority of the country.

Rainfall: April rainfall was near normal (within 20 per cent of April normal) to above normal (120-150 per cent of normal) for most of the country. Additionally, there were many locations on both islands, mainly the southern half of the North Island and the northern half of the South Island, which received well above normal rainfall (more than 150 per cent of normal).

Soil Moisture: As at May 1, soil moisture across the country had increased substantially when compared with March values for much of the North Island. But some areas of the country, particularly Northland, Wanganui-Manawatu, Otago and Southland remain drier than normal.

HIGHLIGHTS:

* The highest temperature was 29.6C, observed at Whakatane on April 7.
* The lowest temperature was -4.2C, observed at Pukaki Aerodrome on April 29
* The highest 1-day rainfall was 197 mm, recorded at Akaroa on April 17.
* The highest wind gust was 146 km/hr, observed at Baring Head on April 17.
* Of the six main centres in April 2014, Auckland was the warmest and sunniest, Dunedin was the coolest and driest, Christchurch was the cloudiest and Wellington was the wettest.
* Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2014 are: Whakatane (1050 hours), Tauranga (947 hours), Auckland (Albany - 913 hours) and Takaka (893 hours).

- NZ Herald

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