Winter weather: 2020 was the warmest on record in New Zealand, driven by climate change – Niwa

If you felt that the big chill never came this year, you would be right; According to Niwa, it was the hottest winter on record in New Zealand.

Seven of the 10 warmest winters have occurred since 2000, increasingly driven by climate change, the “long-term tailwind.”

The national average for 2020 was 9.6 ° C – 1.14 ° C above the 1981-2010 average, taken from Niwa’s seven-station temperature series beginning in 1909, and exceeding the previous record from 2013 at just 0.06 ° C.

Temperatures across the country were generally above or well above average, which would not have surprised skiers with a mediocre season of snowfall on the slopes.

Only a few places had near-average winter temperatures, including Tararua, Kaikōura, and parts of Southland and Otago.

First place was Timaru, with a completely off-season 25.1C on August 30.

The lowest temperature was -12.3 ° C, in Middlemarch on June 14.

Of the six major hubs 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 highest amount of rain in one day was 262mm, recorded at Kaikohe on July 17, and the highest wind gust was 191 km / h, at Cape Turnagain on July 23.

According to Niwa’s 2020 Winter Climate Summary, four main factors drove these high temperatures: subtropical winds, warmer-than-average seas, more sunshine, and climate change.

“It’s really a combination of everyone who made this winter special,” said meteorologist Ben Noll.

The season was characterized by more frequent than normal warm northeast winds, particularly on 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, at 0.5 ° C to 1 ° C, and most notably during August, exerting a greater warming influence on the country air temperatures.

A prevailing high pressure system throughout the country contributed to a sunnier than normal winter in much of the South Island and lower North Island.

All of this combined with the background influence of climate change, the “long-term tailwind at our temperatures”, which resulted in widespread warm conditions during winter.

“There are the more natural climate drivers like SST, the high pressure system and the winds, but then there is the human influence of climate change mixing it all up.

“And all of these ‘natural’ factors can be linked to climate change, as warmer seas are influenced by warmer air temperatures, which are influenced by climate change.”

Increasingly, statistics “tell the story” of climate change, Noll said.

“Seeing seven of the 10 warmest winters since 2000 shows that we really are in a warming world.

“We will still have some cold winters, but that will increasingly become the exception. By 2040, we could be looking back as a normal winter.”

This also meant that bad season on the ski slopes would likely become the norm as well.

“We know there is a strong correlation between cold weather and snow. Also, snowfall acts as a refrigerator, so the more snow there is, the more likely it is to snow.”

Under the Paris agreement, New Zealand has committed to reducing emissions 30% below 2005 levels and 11% below 1990 levels by 2030.

Climate Change Minister James Shaw has tasked the newly formed Climate Change Commission with investigating whether those targets, which sit alongside the government’s zero-carbon target for 2050, are ambitious enough to meet the target. to limit warming to 1.5 ° C above pre-industrial levels. .