Drought
Rainfall deficiencies and water availability

Exceptional November rainfall lifts deficiencies in Queensland

Rainfall for November 2021 was above or very much above average for most of mainland Australia. Nationally, November was the wettest since national records begin in 1900 (122 years), exceeding the previous national record set in November 1973. Large areas of South Australia and adjacent border areas of Western Australia and the south-west Northern Territory, and areas of eastern to central New South Wales and eastern Queensland had their wettest November on record.

Rainfall was below average for western Tasmania, far south-west Victoria and south-east South Australia, and south-west Western Australia.

The patterns of rainfall across Australia are consistent with current climate drivers, with a decaying negative Indian Ocean Dipole and strengthening La Niña generally increasing the chance of rainfall across northern and eastern Australia, while the positive Southern Annular Mode and Madden Julian Oscillation amplified the effects of the primary climate drivers over the month.

The very wet month has resulted in the removal of serious or severe rainfall deficiencies for the period commencing April 2020 in Queensland This includes the Wide Bay–Burnett region, which largely missed out on the La Niña rains of 2020.

The Climate Outlook released on 2 December 2021 indicates rainfall for December to February is likely to be above median for much of the eastern states of Australia, with highest chances for eastern Queensland, eastern New South Wales and eastern Victoria.

20-month rainfall deficiencies

Rainfall for November 2021 was above or very much above average for most of mainland Australia, and highest on record for areas of eastern Queensland. As a result, serious or severe rainfall deficiencies for the period have been removed in Queensland's Capricornia, Wide Bay and Burnett, and Central Highlands districts, and from a pocket of the west of the state near Boulia.

While November rainfall was sufficient to raise totals for April 2020–November 2021 above the lowest 10% of historical observations (decile 1, which corresponds to serious deficiency), it has not completely accounted for below average rainfall over that period, with large areas of the region previously experiencing serious rainfall deficiency still within decile 3 (below average), and rainfall for the period remains more than 200 mm less than average for the 20-month period along Queensland's central to south-east coast.

We anticipate the Bureau will cease formally monitoring this period next month, though drought maps for standard periods from 3 to 48 months will remain available as part of our routine mapping products. If so, this will be the first time since February 2017 that the Bureau has not had an active formally monitored drought period.

Extended dry conditions over eastern Australia

Multi-year rainfall deficiencies which originated during the 2017–2019 drought remain over large parts of the country, despite some lessening following the record-wet November. While there has been a reduction of the area in decile 1 in New South Wales and of the area of lowest on record in eastern Queensland, the accumulated rainfall anomalies remain very large for some areas.

Over the past two years, seasonal conditions have improved over large areas, and water storages have increased across much of the country, especially in the Murray–Darling Basin.

Many areas experiencing rainfall deficiencies for periods longer than 24 months have typically experienced below average rainfall between April and October, which is consistent with the long term trends in rainfall reduction over southern Australia and along the Great Dividing Range as discussed in State of the Climate 2020.

Soil moisture

Root-zone soil moisture (soil moisture in the top 100 cm) for November 2021 was above average across most of Australia, including the Murray–Darling Basin, but close to average for parts of Queensland's Cape York Peninsula, parts of the north and south of Western Australia, parts of the Top End, and for western Victoria and south-east South Australia.

Soil moisture increased across most of Australia compared to the previous month.

Saturated soil conditions, especially across eastern Australia, may result in large inflows into water storages if further rainfall occurs during the coming months. Wet soils, high streamflows, and full storages increase the risk of flooding, particularly in south-east Australia.

• November was Australia's, New South Wales's, South Australia's and the Murray–Darling Basin's wettest November on record, fuelled by a weakening negative Indian Ocean Dipole and La Niña
• It was Australia's wettest spring since the La Niña of 2010, and the tenth-wettest since national records begin in 1900
• Serious rainfall deficiencies for the period commencing April 2020 have been cleared from Queensland following very much above average rainfall during November
• Rapid filling of storages continued in the northern Murray–Darling Basin during the spring season, and many storages are above full capacity; average storage across the northern MDB has risen from around 25% at this time in 2020, to over 85% at the end of November 2021
• Hume dam storage is at its highest level in five years and flows are being released to manage flood risk
• South East and Central Queensland storages have started to increase

Storage levels in the Murray–Darling Basin continue to increase

November rainfall was above to very much above average across the Murray–Darling Basin. This has resulted in rapid filling of the storages in the region which were already reasonably full. The total water storage (accessible) in the Murray–Darling Basin continued to increase and reached 91% of capacity, an increase of 3% over the last month. Compared to the same time last year, when the total storage volume was only 61%, the water storages are in a significantly better position.

The total storage in the northern Basin increased by 8.3% to 90.9% of capacity (4 222 GL) at the end of November. This is the highest level since May 2012 and a significant increase from the same time last year when it was only 24.5%. In the northern Basin, most of the storages are above their full capacities while other are almost full, with exceptions being Split Rock, Windamere, Leslie and Cooby Creek.

The total storage in the southern Basin (comprising more than 80% of the total storage volume in the Basin) increased by 1.2% to reach 90.4% (18 688 GL) of accessible capacity in November. This is considerably higher than the same time last year when it was only 69%. Most of the storages in the southern Basin are at or near full capacity. All three of the very large storages in the southern Basin (Hume, Dartmouth, and Eildon), that comprise 40% of the total storage capacity of the Basin, continued to increase this month. Hume dam is currently at 98.3% of capacity, the highest level since November 2016. During the last three months, the dam was operated in controlled release mode to create airspace and during November the release volume was further increased for safe operations. Climate Outlooks indicate above median rainfall is likely for areas upstream of the dam over summer, which increases the possibility of more release from Hume dam in coming weeks.

The Menindee Lakes system has seen a period of rapid filling during spring 2021 and reached 109% of capacity in November. Flood waters resulting from above average rainfall in the northern Murray–Darling basin moving down the Darling–Barka River have resulted in the highest water levels in the Lakes since November 2012; significantly higher than the same time last year when it was only 23.1% full.

Further detail on individual Murray–Darling Basin catchments can be found in the Murray–Darling Basin Information Portal.

South East Queensland storages yet to see much change despite a wet month

In South East Queensland, the largest storage, Wivenhoe, remained unchanged in November at 39.7% of capacity. Although very much above–average rainfall occurred during the month, the storage levels did not increase. While November rainfall was in decile 10 across all of south-eastern Queensland, the area around Brisbane received rainfall 150–200% of the 1961–1990 average, whereas most other catchments, particularly further inland, received 200–300% of average rainfall for the month. However, the continued decrease of the storage level over recent months did stop and the level is very similar to the same time last year when it was 40.5%.

The water levels of the two large rural systems in South East and Central Queensland, Bundaberg and Nogoa Mackenzie, increased significantly in November. The accessible volume of the Bundaberg system increased to 52.6% from 29.6% of capacity in one month, which is higher than the same time last year when it was 42.8%. In the Nogoa Mackenzie system, by the end of November 2021, the storage level had increased to 22% from 13.3%, much higher than at the same time last year when it was at 9%.