Winter 2018

A mild winter for much of the country and dry in parts of the South Island.

Temperature 

Winter 2018 was New Zealand’s 6th-warmest on record.  Temperatures were above average (+0.51°C to +1.20°C of the winter average) or near average (-0.50°C to +0.50°C of the winter average) for most of the country.  Winter temperatures were well above average (> +1.20°C of the winter average) for much of north Canterbury, and a few other isolated inland locations. 

Rainfall

Below normal rainfall (50-79% of the winter normal) was observed in eastern and inland parts of Canterbury and Otago.  Rainfall was above normal (120-149% of the winter normal) in isolated parts of Marlborough, Kapiti Coast, Manawatu and the Bay of Plenty. 

Soil moisture

At the end of winter 2018, slightly drier than usual soils were present in southern Hawke’s Bay, north Canterbury, and central Otago.  Soil moisture levels were above normal for the time of year in parts of coastal Otago and Marlborough, as well as around coastal Gisborne.  Soil moisture levels were generally near normal for the time of year across the rest of the country.

Overview

Winter 2018 got off to a relatively settled start for much of the South Island, with record or near-record low rainfall totals for June in several locations. In contrast, northern and eastern parts of the North Island bore the brunt of heavy rainfall events which resulted in significant flooding about East Cape (see Highlights and extreme events section for further details).  During July, there were more northwesterly air flows than normal. This delivered relatively mild temperatures to the county, with abundant rainfall to the western South Island.  However, July was very dry for eastern areas of New Zealand.  August also saw more northwesterly airflows than normal, resulting in ongoing dryness for many parts of Canterbury and Otago. The variable airflow patterns through the season owed in part to ENSO-neutral conditions (neither El Niño nor La Niña) in the equatorial Pacific. During the winter season, the polar jet stream was weaker than normal to the south of New Zealand. This prevented long-lived cold periods and contributed to a lack of snowfall for some ski areas in the South Island.

Further highlights

  • The highest temperature was 22.3°C, observed at Kaikoura on 21 July.
  • The lowest temperature was -10.4°C, observed at Mt Cook Airport on 3 June.
  • The highest 1-day rainfall was 246 mm, recorded at Milford Sound on 6 July.
  • The highest wind gust was 209 km/hr, observed at White Island on 9 July.
  • Of the six main centres in winter 2018, Tauranga was the warmest, wettest and sunniest, Dunedin was the driest, Christchurch was the coolest, and Wellington was the least sunny.

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Contact

Mr Gregor Macara, Climate Scientist.
NIWA Wellington
Tel. 04 386 0509