Australia has coolest year since 2012, wettest November ever

Last year was Australia’s coolest since 2012 as the La Nina weather pattern brought widespread rainfall, though the national mean temperature was still above average.

While cooler than the preceding eight years, Australia’s 2021 national mean temperature was still 0.56 °C warmer than the 1961–1990 average, the Bureau of Meteorology says in its Annual Climate Statement. It was the 19th-warmest year since records began 112 years ago.

Rainfall was boosted by the wettest November on record, with the annual national total 9% above the 1961–1990 average at 509.7mm.

Compared to all years since 1900, rainfall was above average for eastern Victoria, much of NSW, southern and central west Queensland, and parts of WA, the far northern tropics in the Kimberley, Top End and Queensland’s Cape York Peninsula.

The heavy November rainfall contributed to areas of flash flooding and riverine flooding across eastern and south-east Australia, including across large areas of inland NSW and Queensland from November 11, before renewed rainfall from November 21 to the end of the month caused further flooding.

At St Arnaud, in Victoria’s Wimmera, a storm cell dumped two month’s average rainfall in just a couple of hours on November 4, resulting in significant flooding and evacuations.

Heavy rain and hail resulted in damaged crops and in flooding in SA’s Riverland on November 6, while storms in Melbourne brought heavy rainfall to northern and eastern suburbs, and caused flash flooding in some south-eastern suburbs.

Alice Springs Airport recorded its wettest November day on record on the 10th, with the Todd River bursting its banks.

Annual mean temperatures for 2021 were above average for most of northern Australia, Tasmania, and large parts of WA, but below average for parts of inland NSW, compared to the distribution across all years since 1910.

Australia’s 2021 mean maximum temperature was 0.65 °C above average. The mean minimum was 0.45 °C above average. July and August were particularly warm.

Most capital cities had mean high and low temperatures which were within half a degree of average, except Canberra where daytime temperatures were well below average.

Rainfall was within 10% of average for Adelaide and Darwin, above average for Sydney, Hobart and Perth, and well above average for Brisbane and Canberra, which had its wettest year since 2010 and its 5th-wettest on record.

The year brought significant increases in water storages across the Murray–Darling Basin, with many reaching full capacity and a decrease in the dependence on groundwater and desalinated water in many parts of Australia.

“After commencing 2021 at 58% of capacity, water storages in the Murray–Darling Basin experienced significant filling over winter and spring with a number of storages spilling or being operated to avoid spilling. However, storages in south-east Queensland remained low with the largest storage, Wivenhoe, only increasing from 39% to 47% during 2021,” the Bureau said.

Groundwater levels continued to be low, although there were some signs of recovery.