2021 was New Zealand’s hottest year on record - NIWA

Source: 1News

Over the holidays many around the country have been basking in the glorious heat. Now it's official - 2021 has been confirmed as the hottest year on record in New Zealand.

Jandals at a beach.

The record, which is based on the National Institute of Water and Atmospheric Research's seven-station series, began in 1909.

The previous record was set in 2016.

However, in 2021 the nationwide average temperature for was 13.56 degrees - 0.95 degrees above the 1981 to 2010 average.

Annual temperatures in 2021 were above average - 0.51 degrees Celsius to 1.2 degrees higher - for much of Aotearoa.

Meanwhile, in parts Auckland, the Bay of Plenty, Tasman and Fiordland temperatures were even hotter - with NIWA reporting temperatures of 1.2 degrees higher than average.

NIWA says data, "shows that for the country as a whole, 26 per cent of days in 2021 featured below or well below average temperatures, 19 per cent of days had near average temperatures and 55 per cent of days featured above average or well above average temperatures," NIWA said in a statement on Tuesday.

"Frequent high pressure over the North Island and east of New Zealand, which caused more northerly quarter winds than normal, was a contributor to New Zealand’s warmest year on record."

But the warm weather comes with a confronting reality.

"Seven of the past nine years have been among New Zealand’s warmest on record. This trend is consistent with the overall pattern of global warming," NIWA said.

"It was the warmest year on record for 12 locations and a further 50 locations experienced annual average temperatures in the top four warmest on record."

The hottest spell of the year was in late January, with several locations seeing record or near-record high daily maximum and daily minimum temperatures.

"The highest temperature of 2021 was recorded on 26 January at Ashburton. The maximum temperature there reached 39.4 degrees, which is New Zealand’s second-highest January temperature on record, and the country’s 10th-equal hottest temperature on record for all months."

The temperature is surpassed only by a 40 degree recording in Timaru on January 22, 1908.

NIWA said from January 25 to 28, "a very warm air mass originating in Australia combined with westerly foehn winds resulted in widespread record and near-record temperatures across eastern New Zealand".

"Notably, on 26 January, Akaroa reached 38 degrees, shattering its all-time record by 2.5 degrees. Cheviot reached 37.9 degrees, breaking its all-time record by 0.1 degrees, while Timaru also recorded 37.9 degrees, its second hottest January temperature since records began in 1885."

The start of 2021 also featured extended dry spells in the North Island, with the Far North enduring a drought during January.

In February, very dry to extremely dry conditions became widespread across large parts of the North Island, Marlborough and northern Canterbury.

Water restrictions were temporarily implemented in Northland, Auckland, Wairarapa and the Hastings District.

Then mid year, it was the warmest winter on record in 2021, surpassing the record recently set the previous winter.

It was also the warmest June on record, with the nationwide average temperature being 2 degrees above average.

"Several atmospheric rivers, or long, narrow regions in the atmosphere that transport most of the water vapour outside the tropics, affected New Zealand during winter, causing extreme rainfall in some regions," NIWA said.

"This was typically associated with the active phase of the MJO in the Indian Ocean, Maritime Continent, and western Pacific. This was likely connected to the emergence of a negative Indian Ocean Dipole, which refers to warmer than average ocean temperatures in the tropical eastern Indian Ocean.

"For New Zealand, this may have allowed for more tropical moisture to become available to passing weather systems in the mid-latitudes."

Ending the year, New Zealand recorded the warmest November on record and the fourth warmest December on record.