Having monitored it locally (but not this year this surprises me. We have not had the hot blob in the Tasman, there has been no el-Nino and I have not felt the sweltering night time temperatures of previous winters.
Winter weather: 2020 was New Zealand’s warmest on record, fuelled by climate change – Niwa
3 September, 2020
If you felt like the big chill never arrived this year you’d be correct; according to Niwa, it’s been New Zealand’s hottest winter on record.
Seven of the 10 warmest winters have occurred since 2000, increasingly fuelled by climate change – the “long-term tailwind”.
The countrywide average for 2020 was 9.6C – 1.14C above the 1981-2010 average, taken from Niwa’s seven station temperature series which begins in 1909, and pipping the previous record of 2013 by just 0.06C.
Temperatures across the country were generally above or well above average, which would have been no surprise to skiers with a lacklustre season of snowfall on the slopes.
Only a few spots were near average winter temperatures, including Tararua, Kaikōura, and parts of Southland and Otago.
The top spot was Timaru, with a completely out-of-season 25.1C on August 30.
The lowest temperature was -12.3C, at Middlemarch on June 14.
Of the six main centres in winter 2020, Auckland was the warmest, Christchurch was the coolest, Tauranga was the wettest and sunniest, Dunedin was the driest, and Hamilton was the least sunny.
The most rainfall in one day was 262mm, recorded at Kaikohe on July 17, and the highest wind gust was 191km/h, at Cape Turnagain on July 23.
According to Niwa’s Winter 2020 Climate Summary, driving these high temperatures were four main factors: sub-tropical winds, warmer-than-average seas, more sunshine, and climate change.
“It is really a combination of all of those that made this winter a special one,” meteorologist Ben Noll said.
The season was characterised by more frequent warm northeasterly winds than normal, particularly to the North Island, which was associated with a developing La Niña event in the equatorial Pacific.
Sea surface temperatures (SSTs) surrounding New Zealand were also warmer than average – 0.5C to 1C – and most notably during August, which exerted a further warming influence on the country’s air temperatures.
A prevalent high-pressure system over the country contributed to a sunnier-than-normal winter for much of the South Island and lower North Island.
This all combined with the background influence of climate change, the “long-term tailwind to our temperatures”, which resulted in widespread warm conditions during winter.
“There are the more natural climate drivers, like the SST, the high pressure system, and the winds, but then there is the human-made influence of climate change mixing it all up.
“And those ‘natural’ factors can all link back to climate change, as warmer seas are influenced by warmer air temperatures, which are influenced by climate change.”
The statistics increasingly “tell the story well” of climate change, Noll said.
“Seeing seven of 10 warmest winters occurring since 2000 shows we really are in a warming world.
“We will still get the odd cold winter, but that will increasingly become the exception. By 2040, we might be looking back at this as a normal winter.”
This also meant the poor season on the ski slopes would likely become the norm, too.
“We know there is a strong correlation between cold weather and snow. Also snowfall acts as a refrigerator, so the more snow you have the more likely it is to snow.”
Under the Paris accord, New Zealand has pledged to slash emissions by 30 per cent below 2005 levels, and 11 per cent below 1990 levels, by 2030.
Climate Change Minister James Shaw has tasked the recently formed Climate Change Commission to investigate whether those targets – which sit alongside the Government’s zero-carbon 2050 goal – are ambitious enough to meet the UN’s aspirational target of limiting warming to 1.5C above pre-industrial levels.