Climate Summary for April 2015

A wet and warm month for many parts of the country

Rainfall	Rainfall was well above normal (> 149%) or above normal (120-149%) for southern, central and western parts of the North Island, western and northern parts of the South Island, and eastern and inland parts of Canterbury south of Christchurch.  Rainfall was well below normal (< 50%) or below normal (50-79%) for Northland, Gisborne, northern Hawke’s Bay and coastal North Canterbury.
Temperature	April temperatures were above average (+0.51°C to +1.20°C) for most parts of the country.  It was a particularly warm month for West Coast, eastern parts of Canterbury, Kapiti Coast, Manawatu-Whanganui and Taranaki where temperatures were well above average (> +1.20°C).
Soil Moisture	As of 1 May 2015, soil moisture levels were above normal for this time of year for parts of Waikato, Taranaki, Manawatu-Whanganui, eastern Mid-Canterbury, the Mackenzie Country and western Southland.  Soil moisture levels were below normal for this time of year for eastern and northern parts of the North Island, and eastern parts of North Canterbury.
Sunshine	Most of the country recorded near normal (90-109%) or below normal April sunshine.  The exception was Northland and Dunedin, where April sunshine was above normal (110-125%).

Overview

April 2015 gave New Zealand its first real taste of winter for the year, with a polar outbreak in the middle of the month that saw temperatures plummet nationwide, and brought snowfall to very low elevations for southern parts of the South Island.  Overall, the month was characterised by air pressures which were higher than normal to the northeast of New Zealand and south of Australia.  This pressure pattern resulted in a weak north-westerly flow anomaly across the North Island and a weak south-easterly flow anomaly over the South Island.  The northward retreat of the subtropical belt of anticyclones allowed numerous fronts to pass over the country during the month, and these delivered bouts of heavy rain to many parts.  It was particularly wet for southern, central and western parts of the North Island where rainfall totals for the month were well above normal (> 149% of the April normal).  Rainfall was either above normal (120-149% of April normal) or well above normal for western and northern parts of the South Island, and eastern and inland parts of Canterbury south of Christchurch.  In contrast, it was a very dry month for Northland, Gisborne, northern Hawke’s Bay and coastal North Canterbury where April rainfall was well below normal (< 50% of the April normal) or below normal (50-79% of the April normal).  Rainfall was near normal (80-119% of the April normal) for remaining areas of the country.  Such contrasting rainfall was reflected in soil moisture levels that differed considerably between different regions of New Zealand.  As of 1 May 2015, soils were notably drier than normal for Northland and northern Auckland, Gisborne, Hawke’s Bay, coastal Wairarapa and eastern parts of North Canterbury.  Soils were wetter than normal in parts of Waikato, Taranaki, Manawatu-Whanganui, eastern Mid-Canterbury, the Mackenzie Country and western Southland.  Elsewhere, soil moisture levels were nearer to normal for this time of year.

Despite the polar outbreak in mid-April, it was a mild month overall, with at least above average temperatures (0.51-1.20°C above the April average) for the majority of the country.  The exception was south-eastern parts of the South Island, inland parts of Canterbury and western parts of Waikato where temperatures were typically near average (between -0.50°C to +0.50C of the April average).  It was a particularly warm month for West Coast, eastern parts of Canterbury north of Ashburton, Kapiti Coast, Manawatu-Whanganui and Taranaki where temperatures were well above average (> 1.20°C above the April average).  The nation-wide average temperature in April 2015 was 14.1°C (0.9°C above the 1981-2010 April average from NIWA’s seven station temperature series which begins in 1909)^[1].

It was a sunny month for Northland and Dunedin where April sunshine was above normal (110-125% of the April normal).  Remaining parts of the country weren’t so lucky, and received either near normal (90-109% of the April normal) or below normal (75-89% of the April normal) sunshine.

Further Highlights:

• The highest temperature was 30.4°C, observed at Cheviot on 7 April.
• The lowest temperature was -4.8°C, observed at Hanmer Forest on 15 April.
• The highest 1-day rainfall was 206 mm[2], recorded at North Egmont on 8 April.
• The highest wind gust was 170 km/hr, observed at South West Cape on 7 April.
• Of the six main centres in April 2015, Auckland was the warmest and sunniest, Dunedin was the coolest and driest, Hamilton was the wettest and Christchurch was the cloudiest.
• Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2015 (1 January to 30 April) are: New Plymouth (1029 hours), Whakatane (1009 hours), Waipara West (972 hours) and Paraparaumu (970 hours).

Download 

Monthly Climate Summary - April 2015 [633.3 KB] 

Climate statistics for April 2015 [74 Kb PDF]

Contact

For further information, please contact:

Mr Chris Brandolino
NIWA Forecaster – NIWA National Climate Centre
Tel. 09 375 6335, Mobile (027) 886 0014