The Bureau of Meteorology (BoM) said 2021 was the coolest year since 2012 and the wettest year since 2016.
At the end of 2021, no large parts of the country were experiencing drought conditions for the first time in five years.
“For Australia, in 2021 the mean temperature was 0.56 degrees above the average, it made it the 19th warmest year since records began in 1910 but also the coolest year since 2012,” senior climatologist Dr Simon Grainger said.
“2021 was actually almost 0.4 degrees cooler than the average temperature on record from 2011 to 2020.
“It was actually much cooler in 2021 than the last decade.”
However Dr Martin Rice, the Climate Council’s director of research, said 2021 was actually the warmest La Niña year on record.
“Last year was a standout because it was warmer than any previous La Niña year,” he said.
“It is amazing to consider that 2021, a year influenced by a La Niña event, was the coolest year in only one decade, which shows you that 2021 is sitting on an exceptionally strong long-term warming trend,” Climate Councillor Professor Will Steffen said.
“If you zoom out to the bigger picture — over a few decades or longer — there is an underlying, upward trend in temperature driven by human emission of greenhouse gases.”
Temperatures were above average for most of northern Australia, Tasmania, and Western Australia’s west coast while NSW saw below-average temperatures.
Not only was it the coolest year in a decade but it was also the wettest year since 2016.
Dr Grainger said the above-average rainfall helped ease the drought conditions the country had endured between 2017 and 2019, but it did mean there was more flooding.
“Rainfall overall was nine per cent above the average,” Dr Grainger said.
Dr Grainger said November was the wettest month on record, particularly in NSW.
“November was the wettest November since national records began in 1900,” he said.
Above-average rainfall was also recorded in eastern Victoria, southern and central west Queensland and the western parts of Western Australia.
This substantial rainfall caused “significant flooding” across eastern Australia in March and again in November and December.
The BoM said the major rainfall meant major dams, particularly in the Murray Darling Basin, had replenished water levels.
The condition also caused the lower than usual temperatures.
“The combination of La Niña events and the residual effects of Indian Ocean Dipole all contributed to Australia having its wettest November on record,” Dr Grainger said.