Spring Climate Summary

Spring Climate Summary

A dry spring for many parts of the country

Overview

Spring 2015 saw strong El Niño conditions persist in the Tropical Pacific. Overall, the season was characterised by mean sea level pressures that were higher than normal over Australia and the Tasman Sea, while lower pressures than normal occurred to the south-east of New Zealand. This pressure pattern resulted in a south-westerly airflow anomaly over much of the country, which is a characteristic of El Niño during spring. Rainfall was well below normal (< 50% of the spring normal) in Nelson and Marlborough, and below normal (50-79% of the spring normal) in most remaining areas of the South Island. The exceptions were coastal areas of Southland and Otago (south of Oamaru), where rainfall was near normal (within 20% of the spring normal). In the North Island, rainfall was typically below normal in Wellington, Wairarapa, Manawatu-Whanganui, Taranaki, southern and central Waikato and northern Northland. In contrast, rainfall was above normal (120-149% of the spring normal) or well above normal (> 149% of the spring normal) in Gisborne and Hawke’s Bay. This was likely to be as a result of two heavy rain events which occurred in these regions around mid-September and early-November. Remaining areas of the North Island typically received near average rainfall for the season. Soil moisture levels were near normal for many parts of the country in early spring. The notable exceptions were parts of coastal Hurunui, South Canterbury and North Otago where soil moisture levels were below normal for the time of year. Due to the prevalence of south-westerlies during spring, which are typical of El Niño, soils in many eastern areas became increasingly dry as the season progressed. As of 1 December 2015, soil moisture levels were below normal for the time of year for extensive areas of New Zealand, but especially for Canterbury, Nelson, Marlborough, Wellington, Wairarapa, Taranaki, southern Waikato and Northland. Soil moisture levels were above normal in Gisborne,.

For the season as a whole, temperatures were near average (-0.50°C to + 0.50°C of the spring average) across most of the country. The exception was parts of western Waikato, southern Hawke’s Bay, Wairarapa and the inland Canterbury Plains where temperatures were below average (0.51°C to 1.20°C below the spring average). Despite mostly near average temperatures for spring overall, there was noticeable variability from month-to-month. Specifically, many parts of the country observed below average temperatures in September, and above average temperatures (0.51°C to 1.20°C above the spring average) in October. The nation-wide average temperature in spring 2015 was 12.0°C (0.1°C below the 1981-2010 spring average from NIWA’s seven station temperature series which begins in 1909) .

It was a sunny spring for the Far North, inland Bay of Plenty, southern Waikato, Nelson, Marlborough, Canterbury, Otago and Southland where sunshine totals were generally above normal (110-125% of the spring normal). Remaining areas of New Zealand observed near normal spring sunshine totals (within 10% of the spring normal).

Further Highlights:
• The highest temperature was 31.7°C, observed at Hastings on 26 November.

• The lowest temperature was -8.2°C, observed at Naseby Forest on 31 October.

• The highest 1-day rainfall was 291 mm, recorded at Milford Sound on 16 October.

• The highest wind gust was 172 km/hr, observed at Cape Turnagain on 5 October and South West Cape on 7 October.

• Of the six main centres in spring 2015, Auckland was the warmest, Dunedin was the coolest, Christchurch was the driest and sunniest, Hamilton was the wettest and Auckland was the cloudiest.

• Of the available, regularly reporting sunshine observation sites, the sunniest four locations so far in 2015 (1 January to 30 November) are: Blenheim (2519 hours), Whakatane (2476 hours), Appleby (2456 hours) and Lake Tekapo (2423 hours).

Full Report: Spring Climate Summary

ENDS

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