Climate Summary for July 2020

Very wet in Northland, dry for many remaining areas

Rainfall

Rainfall was well above normal (>149% of normal) or above normal (120-149% of normal) for Northland, western Otago and inland parts of Southland. Rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) for parts of all remaining North Island regions, and much of the northern, eastern and inland areas of the South Island.

Temperature

Temperatures were above average (0.51-1.20°C above average) or near average (±0.50°C of average) for most of the country. Above average temperatures were mostly observed in central and northwestern parts of the South Island, and northern, western and southern parts of the North Island.

Soil Moisture

At the end of the month, soil moisture levels were lower than normal for eastern parts of Otago and Canterbury (south of Ashburton). Near normal soil moisture levels were typical for the remainder of the country.

 

Overview

July 2020 mean sea level air pressure was above normal from southern Australia through to the Southern Ocean, with lower than normal sea level pressure from, and especially southeast, of the South Island. This resulted in more westerly winds than normal for the North Island, and more southwesterly winds than normal across the South Island. However, there were episodes of east to northeast air flows, notably in mid-July. This was associated with very heavy rainfall for portions of the upper North Island, particularly in Northland which suffered significant flooding.

There were considerable spatial differences in monthly rainfall totals observed over the country in July. 

 Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) for Northland, western Otago and inland parts of Southland.  Most of Northland’s rainfall occurred during the middle of the month, when a low-pressure system delivered very moist subtropical air to the region.  The relatively high rainfall totals observed in western Otago and inland parts of Southland may be partly attributed to more frequent southwesterly winds observed there during the month.  In contrast, rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) for many remaining areas of the country.  Apart from Northland, parts of all North Island regions observed below normal rainfall, with well below normal rainfall in Wellington.  Rainfall was also well below normal in Marlborough, eastern and inland parts of Canterbury, and North Otago.  It was especially dry in Timaru where just 5 mm of rain (10% of the July average) was recorded.  Tasman, Nelson, and eastern parts of Central Otago observed below normal rainfall for the month. By the end of July, soils were drier than normal in eastern parts of Otago and southern Canterbury, especially about Timaru. Soil moisture levels were typically near normal for remaining parts of the country.

It was a relatively mild July for most of the country. Temperatures were above average (0.51-1.20°C above average) in central and northwestern parts of the South Island, and southern, western and northern parts of the North Island.  Temperatures were typically near average (±0.50°C of average) for Hawke’s Bay, Wairarapa, Kapiti Coast, as well as western and coastal parts of Otago and Southland. Overall, the nationwide average temperature in July 2020 was 8.6°C. This was 0.8°C above the 1981-2010 July average, making it New Zealand’s eleventh-warmest July since NIWA’s seven station temperature series began in 1909.  It has now been 42 consecutive months since New Zealand’s nationwide average temperature was below average.

Further highlights

  • The highest temperature was 20.0°C, observed at Whangarei on 16 July and Kaitaia on 18 July.
  • The lowest temperature was -8.9°C, observed at Tara Hills (Omarama) on 16 July and Middlemarch on 18 July.
  • The highest 1-day rainfall was 262 mm, recorded at Kaikohe on 17 July.
  • The highest wind gust was 191 km/h, observed at Cape Turnagain on 23 July.
  • Of the six main centres in July 2020, Auckland was the warmest, Wellington was driest and sunniest, Hamilton was the wettest, Christchurch was the coldest, and Dunedin was the least sunny.
  • Of the available, regularly reporting sunshine observation sites, the sunniest four areas in 2020 so far are Bay of Plenty (1583 hours), Greater Nelson (1529), Taranaki (1520 hours) and Marlborough (1456 hours).

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Research subject: ClimateRainfallWeather