Using data from 1 January to 30 November 2021, we can summarise the year-to-date status of Australia's climate and water resources and provide an indication of the possible end of year values and rankings for Australia's mean annual temperature and area averaged rainfall.
- National mean temperature for January to November 2021 was 0.51 °C above the 1961–1990 average.
- 2021 is on track to be the coolest year since 2012, and likely to be outside the 15 warmest years since national temperature records began in 1910.
- Temperatures for January to November were above average to very much above average for most of northern Australia, Tasmania, and Western Australia's west coast; but below average for parts of inland New South Wales, and around the border of Western Australia and the Northern Territory.
- Rainfall for January to November was 10% above the 1961–1990 average.
- Above average rainfall was observed for much of Tasmania, Victoria, New South Wales, southern and central west Queensland, the South West Land Division in Western Australia, and large parts of the far northern tropics.
- Rainfall for the 11 months to November was below average only for a few small pockets, including around the border of South Australia and Victoria.
- 2021 is likely to be wetter than average overall; assisted by Australia's wettest November on record.
- After commencing 2021 at 58% of capacity, water storages in the Murray–Darling Basin experienced significant filling over winter and spring.
What has the temperature been like?
For Australia as a whole, the mean temperature for January to November was +0.51 °C above the 1961–1990 average. This ranks as the 22nd-warmest value for the January–November mean temperature in the 112 years of national records since 1910. Mean temperatures for January to November were above average to very much above average for most of Queensland, the Northern Territory, around the coast of Western Australia, and Tasmania. Mean temperatures were cooler than average for much of central New South Wales west of the ranges, and for a large area spanning the south-west of the Northern Territory and north-eastern Interior District of Western Australia.
Australia's maximum temperature for January to November was warmer than average, with an anomaly of +0.59 °C. Australia's minimum temperature for January to November was also warmer than average, with an anomaly of +0.43 °C.
Heat was persistent across the north during the dry season, particularly in spring. Heat building from late September led to severe to extreme heatwave conditions affecting the Kimberley and Top End during October. Heatwave conditions affected parts of the north again in November.
Where has it rained?
For Australia as a whole, January to November rainfall was 10% above average. Rainfall for the 11 months to November was above average for much of Tasmania, Victoria, New South Wales, southern Queensland extending into the central west, the South West Land Division in Western Australia, and large parts of the far northern tropics in the Kimberley, Top End, and Queensland's Cape York Peninsula. Rainfall was below average for a few pockets, most notably along the Victoria–South Australia border, and in the central north of the Northern Territory.
A major rain event affected many parts of eastern and central Australia in the second half of March. The highest rainfall totals occurred in coastal New South Wales, with the week ending 24 March 2021 the wettest week for the region since national daily records began in 1900. Extensive heavy rainfall also occurred over large inland areas and widespread significant flooding resulted in both coastal and some inland rivers. For more details see Special Climate Statement 74.
A complex low pressure system in early June produced low temperatures, heavy rainfall, and damaging winds across Victoria that did significant damage in some regions and cut power to more than 200,000 people. Major flooding occurred in multiple West Gippsland catchments after more than 200 mm of rain fell during the 24 hours to 9am on 10 June. Daily rainfall records were set across a number of stations in Victoria and major flooding resulted in multiple catchments.
It was the wettest November on record for Australia as a whole, surpassing the previous November record set in 1973. Rainfall was above or very much above average for most of mainland Australia with thunderstorms and periods of heavy rainfall a frequent occurrence across the south-east and Queensland during the month. Flooding occurred across large areas of inland New South Wales and large areas of Queensland. Serious to severe rainfall deficiencies which had persisted in south-eastern Queensland since April 2020 were removed by this event.
What does this mean for water storages?
The major water storages in the Murray–Darling Basin have seen significant recovery in 2021, with total water storage (accessible) in the Murray–Darling Basin increasing over the year, and particularly benefiting from strong inflows from winter into spring. Totals across major storages in the Basin had reached 91% of capacity at the end of November, placing storages in a significantly better position than at the same time in 2020, when the total storage volume was only 61%.
The recovery has been particularly notable over the northern Basin, which reached 90.9% of capacity at the end of November, the highest level since March 2012. Most of the storages in the southern Basin were at or near full accessible capacity at the end of November.
In the North East Coast drainage division, which takes in much of eastern Queensland, low rainfall over the past three wet seasons had seen storage levels show a significant drop year-on-year, with limited recovery over summer into autumn. Total accessible storage across the drainage division were at 55% of capacity at the end of November, having dropped to 48.8% at the start of November, comparable to total storage volume at the same time last year.
The water level in Wivenhoe, the largest storage for South East Queensland, decreased to 36.5% of capacity at the end of February 2021. The storage increased only slightly over autumn, with little change over winter, before gradually declining again over spring and falling to 39.7% of capacity at the end of November, similar to the level at the same time in 2020.
What is the outlook for the calendar year?
Rainfall averaged across Australia is likely to be above the 1961–1990 average for the calendar year. January to November rainfall was 10% above average, bolstered by the country's wettest November in the 122 years since national records begin in 1900. Climate outlooks suggest that December rainfall is likely to be above average for most of the eastern states, but below average for large parts of the western half of Australia, and part of western Tasmania.
December maximum temperatures are likely to be warmer than average for most of Western Australia, the Northern Territory, Victoria and south-east South Australia, and Tasmania, but cooler than average for much of New South Wales and southern Queensland. December minimum temperatures are likely to be warmer than average for the majority of Australia.
Taken together with the January–November observations, this means the 2021 calendar year is unlikely to be amongst Australia's top fifteen warmest years on record, but will most likely be amongst the next ten warmest (i.e. the final rank is anticipated to be between 25th- and 15th-warmest). This will also make 2021 the coolest year since 2012, when the conclusion of the moderately strong 2011–12 La Niña brought cooler and wetter conditions for the first half of the year.
What has been driving weather in 2021?
One La Niña fades, another emerges
After emerging in winter 2020, La Niña persisted in the tropical Pacific through summer 2020–21, with a neutral El Niño–Southern Oscillation (ENSO) state returning during March 2021. ENSO remained neutral through winter, before signs of La Niña development were again detected in early spring, with the event becoming established in late November as La Niña patterns firmed.
La Niña typically brings above average rainfall to much of northern and eastern Australia when it is active, and is one of four drivers contributing to outlooks for above median rainfall for eastern Australia during December 2021. The others are a positive Southern Annular Mode (SAM), warmer than average sea-surface temperatures around Australia's northern tropics, and a decaying negative Indian Ocean Dipole (IOD). The negative IOD had been the dominant driver since late May.
On 31 October 2021 the World Meteorological Organization (WMO) released its provisional report on the State of the Global Climate in 2021, based on data for the first nine months of 2021. The WMO reported that 2021 is likely to between the fifth- and seventh-warmest years on record for the globe, with the past seven years (2015 to 2021) on track to be the seven warmest on record.
On 9 August 2021 the Intergovernmental Panel on Climate Change (IPCC) released its Sixth Assessment Report for Working Group I. It found that global surface temperature was 1.09 °C, with an estimated range of 0.95 to 1.20 °C, higher in 2011–2020 than in 1850–1900.