Autumn 2020

A dry autumn for most areas of the country

Rainfall 

Rainfall totals were below normal (50-79% of the autumn normal) or well below normal (<50 % of the autumn normal) in parts of nearly every New Zealand region. The exceptions were West Coast, Marlborough, Wellington and Wairarapa where near normal (80-119% of the autumn normal) rainfall totals were observed.

Soil moisture

An ongoing lack of rainfall throughout autumn resulted in below normal soil moisture for many parts of the country.  Meteorological drought receded significantly during March, but remained in place across parts of Northland, Auckland, and far northern Waikato in early April, with severe meteorological drought across the Coromandel Peninsula. By the end of autumn 2020, soils were drier than normal for many northern, central and eastern parts of the North Island, as well as eastern, inland and southern parts of the South Island. Soil moisture was generally near normal for remaining parts of the country.

Temperature

Temperatures across the country were mostly near average (within 0.50°C of the autumn average).


Overview

Autumn 2020 was characterised by air pressures that were generally near normal over the country and lower than normal over the Tasman Sea. This was associated with slightly more westerly airflows than normal over the country. The main theme for the season was an ongoing lack of rainfall, with many parts of the country receiving considerably less rainfall than usual. Notably, it was the driest autumn on record for Auckland, Tauranga, and parts of southern Otago.  The lack of rainfall meant drier than usual soils and meteorological drought were a feature for many parts of the country during autumn 2020.  This created considerable water shortage issues, particularly in places which had also observed a dry summer such as Northland, Auckland, Waikato and Hawke’s Bay.

Autumn temperatures were near average for most New Zealand locations.  This was reflected by the nationwide average temperature for autumn 2020, which was 13.4°C (0.1°C above the 1981-2010 average from NIWA’s seven station temperature series which begins in 1909). The season got off to a hot start, with record or near-record high autumn temperatures recorded during the early days of March (refer to the highlights and extreme events section for further details). Cheviot recorded 32.8°C on 3 March, which was New Zealand’s highest temperature recorded during autumn 2020.  This was closely followed by Hanmer Forest, which recorded 32.6°C on 2 March; Hanmer Forest’s highest autumn temperature since records began in 1906. Heavy frosts struck inland parts of the North Island towards the latter part of May, with Ohakune and Turangi each observing their coldest autumn temperature on record (-6.7°C and -5.6°C, respectively).

Further Highlights:

  • The highest temperature was 32.8°C observed in Cheviot on 3 March.
  • The lowest temperature was -8.2°C, observed at Middlemarch on 31 May.
  • The highest 1-day rainfall was 219 mm, recorded at Milford Sound on 21 May.
  • The highest wind gust was 161 km/h, observed at South West Cape on 30 April.
  • Of the six main centres in autumn 2020, Auckland was the warmest, Tauranga was the sunniest, Wellington was the wettest, and Dunedin was the driest, coolest, and least sunny.

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Climate Summary Autumn 2020

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Research subject: ClimateWeather