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Climate Summary for May 2022

Third-warmest May on record

Temperature

Temperatures were above average (0.51-1.20°C above average) or well above average (>1.20°C above average) for most of the country. It was a particularly warm May in parts of Southland, Otago, inland Canterbury and the West Coast, where mean temperatures were more than 2°C higher than average.

Rainfall

Rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) in parts of Northland, Auckland, Gisborne, Hawke’s Bay, the Wairarapa, Canterbury (south of Christchurch), Otago and southwestern Southland.  Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) for northern parts of inland Canterbury and the West Coast, Manawatū-Whanganui, much of Taranaki, and inland portions of Bay of Plenty and Waikato.  

Soil Moisture

At the end of May, drier than normal soils were prominent for Otago, eastern and inland Canterbury about and south of Christchurch, southern Wairarapa, northern Waikato, Auckland, and eastern and northern parts of Northland.  Soils were wetter than normal for parts of Manawatū-Whanganui, Hawke’s Bay and coastal Gisborne.

Overview

May 2022 mean sea level air pressure was above normal over and to the east of Aotearoa New Zealand. Overall, this resulted in more northerly airflows than usual over much of the country – a pattern aided by continuing La Niña conditions.  The weather was generally settled and warm for the first half of the month, although a heavy rainfall event in early May caused flooding in parts of the West Coast.  During the second half of May, the weather turned more unsettled as several intense low pressure systems and associated cold fronts crossed New Zealand.  These systems brought powerful winds, areas of heavy rain, and numerous thunderstorms, one of which produced a possible tornado in Levin that caused considerable damage to many structures (see Highlights and extreme events section for further details).

Temperatures were above average (0.51-1.20°C above average) or well above average (>1.20°C above average) in every region of New Zealand.  It was the third-warmest May on record in New Zealand.  The nationwide average temperature in May 2022 was 12.6°C. This is 1.8°C above the 1981-2010 May average from NIWA’s seven station temperature series which begins in 1909.  Of the four warmest Mays on record, all have occurred since 2011.

The very warm air temperatures were a result of more frequent northerly airflows, ongoing warmer than average sea surface temperatures (SSTs) around the country, and climate change.  Monthly SST anomalies were the largest on record for May in the west of the North Island and the north, west, and east of the South Island (1.9˚C, 2.0˚C, 1.8˚C, and 1.9˚C above average respectively since records began in 1982).

May rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) in parts of Northland, Auckland, Gisborne, Hawke’s Bay, the Wairarapa, Canterbury (south of Christchurch), Otago, and southwestern Southland.  It was particularly dry in Lauder, Ranfurly and Timaru, where just 12 mm, 13 mm and 14 mm of rainfall was recorded, respectively.  In contrast, rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) for northern parts of inland Canterbury and the West Coast, Manawatū-Whanganui, much of Taranaki, and inland portions of Bay of Plenty and Waikato.  The wettest locations compared to normal were Westport and Levin, which recorded 213% and 206% of normal May rainfall, respectively.

Further Highlights:

  • The highest temperature was 25.6°C, observed at Rangiora on 2 May, and Hastings on 19 May.
  • The lowest temperature was -6.9°C, observed at Middlemarch on 28 May.
  • The highest 1-day rainfall was 115 mm, recorded at Milford Sound on 7 May.
  • The highest wind gust was 193 km/h, observed at Cape Foulwind on 20 May.
  • Of the six main centres in May 2022, Auckland was the warmest, Tauranga was the sunniest, Dunedin was the driest, Christchurch was the coolest, Hamilton was the wettest and Wellington was the least sunny.
  • Of the available, regularly reporting sunshine observation sites, the sunniest four locations in 2022 so far are Taranaki (1290 hours), Bay of Plenty (1203 hours), Greater Nelson (1194 hours) and Kāpiti Coast (1170 hours).

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