Climate Summary for August 2013

Warmest August on record for NZ.  Dry in many parts; wet in the east and north of the North Island.

Temperature 

Record or near record-high August mean temperatures recorded throughout the North Island and South Island, with many locations at least 2.0°C above August average.  Well above average temperatures (more than 1.2°C above August average) throughout most of New Zealand.  The exception was areas of Northland, Auckland and western Waikato where temperatures were in the above average range (0.5-1.2°C above August average).  The nation-wide mean temperature was 1.9°C above the August average, based on NIWA’s seven-station temperature series, making this the warmest August on record since 1909.

Rainfall

Well below normal rainfall (less than 50 percent of August normal) for southwestern and eastern Southland, as well as parts of South Otago and Central Otago, and the McKenzie Country.  Below normal rainfall (50-79 percent of August normal) in most remaining areas of Southland and Otago, as well as coastal and inland Canterbury south of Christchurch, Wellington, Wanganui and parts of Waikato.  In contrast, well above normal rainfall (more than 150 percent of August normal) in parts of Hawke’s Bay and Gisborne.

Sunshine

Above normal sunshine (110-125 percent of normal August sunshine) for South Otago, and western parts of Southland and Otago.  Below normal sunshine (75-90 percent of normal August sunshine) throughout Nelson, Marlborough, the northern West Coast, Wellington, western Bay of Plenty and parts of Waikato and Auckland.  Near normal sunshine elsewhere (within 10 percent of normal August sunshine).

Soil moisture

As at 1 September 2013, most soils throughout New Zealand were at normal soil moisture levels for the time of year.  In isolated parts of Central Otago, coastal North Otago and about Kaikoura, soils were wetter than normal for the time of year.

Overview

August 2013 was characterised by mean sea level pressure (MSLP) which was much lower than normal across all of New Zealand, with strongly negative anomalies to the south of Australia.  In contrast, MSLP anomalies were well above normal to the east of New Zealand. These regional pressure patterns resulted in more frequent northerly and north-easterly flows across the country, resulting in high mean temperatures for the time of year across much of the country.

A very warm August was experienced throughout New Zealand.  Mean temperatures for August were well above average (more than 1.2°C above August average) across almost the entire South Island, and most parts of the North Island.  The exception was areas of Northland, Auckland and western Waikato where temperatures were in the above average range (0.5-1.2°C above August average).  Mean temperatures of at least 2.0°C above average for August were recorded in inland parts of Southland, Otago, and Canterbury, as well as Christchurch, Banks Peninsula, West Coast, Manawatu, Taranaki, Bay of Plenty, and Waikato.  The nation-wide average temperature in August 2013 was 10.6°C, (1.9°C above the 1971-2000 August average) from NIWA’s seven-station temperature series which begins in 1909.  August 2013 recorded the highest August mean temperature on record for the seven-station series.

August was a dry month for southwestern and eastern Southland, as well as parts of South Otago and Central Otago, and the McKenzie Country.  Well below normal rainfall (less than 50 percent of August normal) was recorded at those locations.  Below normal rainfall (50-79 percent of August normal) was recorded in most remaining areas of Southland and Otago, as well as coastal and inland Canterbury south of Christchurch, Wellington, Wanganui and parts of Waikato.  In contrast, August was a wet month for Gisborne and Hawke’s Bay.  Well above normal rainfall (more than 150 percent of August normal) was recorded throughout those regions, with some areas towards the coast recording more the double their August normal rainfall.  Above normal rainfall (120-140 percent of August normal) fell in eastern parts of Northland.  Near normal rainfall was experienced elsewhere (within 20 percent of August normal rainfall).  As at 1 September 2013, most soils throughout New Zealand were at normal soil moisture levels for the time of year.  In isolated parts of Central Otago, coastal North Otago and about Kaikoura, soils were wetter than normal for the time of year.

Sunshine hours for August were above normal (110-125 percent of normal August sunshine) for South Otago, and western parts of Southland and Otago. Below normal sunshine (75-90 percent of normal August sunshine) was recorded throughout Nelson, Marlborough, the northern West Coast, Wellington, western Bay of Plenty and parts of Waikato and Auckland.  Near normal sunshine was experienced elsewhere (within 10 percent of normal August sunshine).  Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2013 (January to August) are: Whakatane (1800 hours), New Plymouth (1706 hours), Blenheim (1604 hours) and Lake Tekapo (1591 hours).

Further Highlights:

  • The highest temperature was 22.1 °C, recorded at Kaitaia on 13 August.
  • The lowest temperature was -8.0°C, observed at Lake Tekapo on 28 August.
  • The highest 1-day rainfall was 155 mm, recorded at North Egmont, on 8 August. 
  • The highest wind gust was 154 km/hr, at South West Cape, on 28 August.
  • In August 2013, Auckland was the wettest and warmest, Christchurch was the coolest, Dunedin was the driest, Tauranga was the sunniest, and both Wellington and Hamilton were the cloudiest.
  • Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2013 (January to August) are: Whakatane (1800 hours), New Plymouth (1706 hours), Blenheim (1604 hours) and Lake Tekapo (1591 hours). 

Full report

Full details of the August 2013 climate summary (PDF 786 KB)

Climate statistics table

Climate statistics for August 2013 (PDF 79 KB)

For further information, please contact:

Dr Brett Mullan

Principal Scientist, Climate Variability and Change, NIWA Wellington

Tel. 04 386 0508