National Climate Summary: Autumn 2013 - A warm autumn

[Full document: Climate_Summary_Autumn_2013_FINAL.pdf]

National Climate Summary: Autumn 2013

Issued: 5 June 2013

A warm autumn; dry and sunny to start with, followed by more unsettled weather

Rainfall It was a wet autumn for parts of: Auckland, Waikato, Kapiti Coast, Marlborough, Nelson, and Tasman, with almost 150 percent of normal autumn rainfall. Rainfall was below normal (50-80 percent of autumn normal rainfall) in parts of: Hawke’s Bay, the West Coast of the South Island, inland Canterbury, and Central Otago. Near normal rainfall totals (between 80 and 120 percent of autumn normal rainfall) were observed elsewhere.

Temperature A warm autumn, with well above average temperatures (more than 1.2°C above the autumn average) in the Bay of Plenty and parts of Waikato. Above average temperatures (0.5-1.2°C above the autumn average) throughout the rest of the North Island and across the South Island, except for parts of inland Canterbury where mean temperatures were near average (within 0.5°C of the autumn average).

Sunshine Autumn sunshine was near normal for most of the country (90-110 percent of normal). Below normal sunshine (75-90 percent of autumn normal) for parts of northern and eastern South Island. In contrast, it was very sunny for King Country and west coast of the South Island south of Franz Josef (more than 125 percent of autumn normal sunshine).

Soil moisture As at 1 June, below normal soil moisture levels for the time of year were observed in Hawke’s Bay and Wairarapa, as well as around the Queenstown Lakes district. Near normal soil moisture levels were evident elsewhere, except for Marlborough, Kaikoura Coast, coastal Otago, and coastal southern Canterbury, where soils were much wetter than usual for the time of year.

National Climate Summary: Autumn 2013 Issued: 5 June 2013

Overview

Autumn 2013 as a whole was characterised by lower pressures than normal over New Zealand and the Tasman Sea, which resulted in a predominant northeasterly flow over the country for the season. Early autumn was characterised by high pressure systems which were stationary over the country and kept rain-bearing systems away. As a result, early autumn was very dry and sunny

throughout most of the country. Mid-late autumn was characterised by more unsettled weather associated with low pressure systems, with numerous rain-bearing fronts bringing heavy rainfall to some parts of the country. Notable events include heavy rainfall in the Bay of Plenty on 20 April and Nelson and Tasman on 21 April, and widespread snowfall which affected Canterbury, Otago, and Southland on 28 May.

Overall, it was a wet autumn for parts of: Auckland, Waikato, Kapiti Coast, Marlborough, Nelson, and Tasman, with almost 1.5 times (150 percent) normal autumn rainfall. However, rainfall was below normal (50-80 percent of autumn normal rainfall) in parts of: Hawke’s Bay, the West Coast of the South Island, inland Canterbury, and Central Otago. In general, near normal rainfall totals (between 80 and 120 percent of autumn normal rainfall) were observed elsewhere in New Zealand.

As at 1 June, below normal soil moisture levels for the time of year were observed in Hawke’s Bay and Wairarapa, as well as around the Queenstown Lakes district. Near normal soil moisture levels were evident elsewhere, except for Marlborough, Kaikoura Coast, coastal Otago, and coastal Canterbury (south of Banks Peninsula), where soils were much wetter than usual for the time of year.

It was a warm autumn for most of the country, with mean temperatures well above average (more than 1.2°C above the autumn average) in the Bay of Plenty and parts of the Waikato region. Temperatures were above average (0.5-1.2°C above the autumn average) throughout the remainder of the North Island and across the South Island, except for parts of Marlborough and inland Canterbury where mean temperatures were near average (within 0.5°C of the autumn average). The nation-wide average temperature in autumn 2013 was 13.9°C (0.7°C above the 1971-2010 autumn average, using NIWA’s seven-station temperature series which begins in 1909).

Sunshine was near normal for most of the country for autumn (sunshine hours between 90 and 110 percent of autumn normal). Below-normal sunshine hours were recorded in some areas of the northern and eastern South Island. In contrast, for some areas in the King Country, and on the West Coast of the South Island south of Franz Josef, sunshine hours were well above normal (more than 125 percent of autumn normal). Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2013 (January to May) are: Whakatane (1288 hours), New Plymouth (1272 hours), Blenheim (1162 hours) and Paraparaumu (1160 hours).

Further Highlights:

• The highest temperature was 32.9 °C, recorded at Napier on 18 March.

• The lowest temperature was -7.1°C, observed at Motu on 29 May.

• The highest 1-day rainfall was 208 mm, recorded at Milford Sound on 24 March.

• The highest wind gust was 170 km/hr, at South West Cape, on 26 May.

• Of the six main centres in autumn 2013, Tauranga was the warmest, wettest, and sunniest, Dunedin was the coolest and cloudiest, and Christchurch was the driest.

[Full document: Climate_Summary_Autumn_2013_FINAL.pdf]

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