Spring 2018

Spring 2018: a season of weather swings for New Zealand

Temperature 

Temperatures were near average (-0.50°C to +0.50°C of the spring average) for much of the country. Pockets of below average temperatures (-0.51°C to -1.20°C of the spring average) were observed in coastal Canterbury. A few locations across the west of the South Island recorded above average temperatures (+0.51°C to +1.20°C of the spring average), as did a few isolated locations across interior Gisborne.

Rainfall

Well above normal rainfall (>149% of the spring normal) was observed in Otago and lower Canterbury, as well as across Hawke’s Bay. Rainfall was generally above normal (120-149% of the spring normal) for the remainder of the east of both islands. Rainfall was below normal (50-79% of the spring normal) in parts of Auckland, Manawatu-Wanganui, Taranaki, Tasman, Nelson, Marlborough, and the northern West Coast.

Soil moisture

At the end of spring 2018, drier than normal soils were present in Manawatu-Wanganui, Tasman, Nelson, Marlborough, and in pockets along the West Coast. Soil moisture levels were above normal for the time of year in the east of both islands, as well as across the Coromandel Peninsula and parts of the Far North.

Overview

Early in the season, spring 2018 was defined by frequent high pressure systems, particularly over and to the southwest of New Zealand. This influenced more southeasterly wind flows than normal and led to below normal rainfall across interior and western parts of both islands during September and across much of the North Island and the western South Island during October. The tables were turned during November, with lower than normal sea level pressure over the Tasman Sea and higher than normal sea level pressure to the south of the country. This pressure ‘squeeze’ influenced several extreme rainfall events in eastern and inland parts of New Zealand, with century-old rainfall records being broken in some locations.

The continuation of ENSO-neutral conditions (neither El Niño nor La Niña) contributed to the variable air flow patterns observed across New Zealand through the season. Warmer than average Tasman Sea surface temperatures may have been associated with the mild yet active November pattern.

Further highlights

  • The highest temperature was 31.2°C, observed at Cheviot and Kaikoura on 8 November.
  • The lowest temperature was -7.5°C, observed at Mt Cook Airport on 13 October.
  • The highest 1-day rainfall was 326 mm, recorded at Arthur’s Pass on 8 November.
  • The highest wind gust was 169 km/h, observed at Cape Turnagain on 1 November.
  • Of the six main centres in spring 2018, Auckland was the warmest and driest, Tauranga was the sunniest, Christchurch was the coolest, and Wellington was the wettest, and least sunny.

Download

Climate Summary for Spring 2018 [PDF 630KB]

Contact

Mr Ben NollMeteorologist, NIWA Auckland
Tel. 09 375 6334

Research subject: Climate