Warm snap lasts nearly four years
New Zealand’s long stretch without a cold month continues, as records show the last colder-than-average month was January 2017.
For those who’ve lost track of time, that was the month Donald Trump was sworn in as the 45th President of the United States.
In the almost four years since, temperature stations have recorded 24 above-average months and 23 average ones, but none meeting the National Institute of Water and Atmospheric Research (Niwa) ‘‘cold month’’ definition of at least
0.5 degrees Celsius below the 1981 to 2010 average.
All the hot months were at least 0.5C above average.
Niwa has declared 2020 the seventh-warmest year on record in New Zealand, meaning five of the seven hottest years recorded have now occurred since 2013. It was also an exceptionally dry year in many places, with Auckland and Hamilton each recording their driest years since records began.
Globally, 2020 was a scorcher: It tied with 2016 as the world’s hottest year, according to European Union satellite data from the Copernicus Climate Change Service – 1.25C above pre-industrial times – and the hottest year for Europe.
In New Zealand, the average temperature last year was 0.63C above the 1981–2010 average.
The comparison is not the same as the increase from pre-industrial times, which is over 1C already – roughly in keeping with the global average increase since fossil fuel use took off. A growing number of countries are aiming to stop global heating before it tops 1.5C, after a 2018 report found doing so would drastically improve water insecurity, food supply disruption, property damage and poverty compared with letting the world get above 2C.
New Zealand’s hottest year remains 2016, when the nationwide average temperature was 0.84C above the 1981–2010 average.
Climate scientist James Renwick said the heating trend was as clear here as it was around the world.
‘‘Over the past 23 years, only four have been cooler than the 1981-2010 normal. In the first 23 years of the record, since 1909, only four years were warmer than the 1981-2010 normal,’’ he said.
‘‘Even though we do not see each year being successively warmer than the last, the warm years are piling up.’’
Of the six main centres in 2020, Auckland was the warmest, Dunedin was the coolest, Wellington was the wettest, Christchurch was the driest, Tauranga was the sunniest and Dunedin was the least sunny, according to Niwa.
The year started with smoke and haze from the Australian bushfires affecting New Zealand on January 1.
Last year’s highest temperature, 38.2C, happened in Gisborne on January 31, while the lowest was in Middlemarch in June (minus 12.3C).
In February, Wha¯nga¯rei, Whitianga and Whakata¯ne had their hottest days since records began for those areas in the 1960s (Wha¯nga¯rei, Whitianga) and 70s (Whakata¯ne). Auckland had its longest-ever drought, lasting
47 days, though Blenheim’s drought was longer at 64 days.
A hot and dry start to the year in most places gave way to a wet winter in the north of the North island. The country had its warmest winter on record, with very low snow levels on Aoraki/Mt Cook, before a late cold break in September delivered late snow to Southland and Otago.
October was dry, with strong winds fanning a destructive fire at Lake Ohau. Napier had its secondwettest day ever in November.
By December, the Far North had water restrictions.
Niwa principal scientist Chris Brandolino said the next three months were expected to bring above-average temperatures for most of New Zealand.