Rainfall deficiencies and water availability

Little change to deficiencies in southern coastal Queensland

Rainfall for September 2021 was below average for the southern half of Western Australia, much of South Australia, much of the east coast between the Central Tablelands in New South Wales and the Wide Bay and Burnett District in Queensland, and for north-east Tasmania. For much of coastal South Australia rainfall for the month was very much below average (amongst the lowest 10% of historical observations for the month).

Areas of Queensland's Capricornia, Wide Bay and Burnett districts, extending west into the Central Highlands District have been experiencing deficiencies for the period commencing April 2020. Average or below average rainfall over these areas during September has seen little change in these deficiencies.

Elsewhere, rainfall deficiencies established during the drought of 2017–2019 remain over very large parts of the country, also with little change, and may persist for some time.

Serious rainfall deficiency means an area has received rainfall in the lowest 10% of historical observations for a specified period, compared to all similar periods since 1900 spanning the same calendar months, while severe rainfall deficiency means rainfall totals in the lowest 5% of historical observations.

The Climate Outlook released on 30 September 2021 indicates October to December rainfall is likely to be above median for most areas of Australia, with a greater than 80% chance of above median rainfall over much of the south-east mainland. However, western Tasmania is likely to see below median rainfall.

18-month rainfall deficiencies

Rainfall for south-eastern Queensland and the Wide Bay and Burnett District was below average during September 2021, and generally near average for the remainder of the south-eastern quarter of Queensland. As a result there has been little change to existing rainfall deficiencies.

Serious or severe rainfall deficiencies for the period commencing April 2020 persist in the Capricornia and Wide Bay and Burnett districts and extend west into the Central Highlands District in Queensland, and in a pocket of the west of the state near Boulia.

Some isolated areas of deficiencies persist in central regions of Western Australia that missed out on above average winter rain that fell further to the south.

Extended dry conditions over eastern Australia

Multi-year rainfall deficiencies, which originated during the 2017–2019 drought, remain over large parts of the country due to the extremely low accumulated rainfall totals experienced over this extended period. 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.

The 2020–21 La Niña saw improvement of conditions over parts of eastern Australia, although the end of La Niña saw April and May 2021 drier than average across much of mainland Australia, particularly in the south-east. The development of a weak negative Indian Ocean Dipole during June 2021 led to above average June and July rainfall for much of the coast of the southern mainland and across the south-eastern mainland away from the east coast, with September also wetter than average for much of inland New South Wales and eastern Victoria.

Further periods of above average rainfall are needed to continue the recovery, especially in parts of Queensland, parts of South Australia and far west New South Wales, and East Gippsland in Victoria.

Many areas experiencing rainfall deficiencies for periods longer than 24 months have typically experienced below average rainfall between April and October. The role of climate change in rainfall reduction over southern Australia and along the Great Dividing Range is discussed in State of the Climate 2020. Parts of south-west, south-east, and eastern Australia—including parts of south-east Queensland and southern and eastern New South Wales—have seen substantial declines in cool-season (April to October) rainfall in recent decades.

Soil moisture

Root-zone soil moisture (soil moisture in the top 100 cm) for September 2021 was generally above average across the north of Australia, and below average for parts of southern to central Queensland, much of the southern two thirds of Western Australia, and most of South Australia.

Soil moisture was above average in eastern Victoria following a very wet September, and also above average in parts of eastern New South Wales inland of the Divide, around the border of New South Wales–South Australia–Queensland, and in parts of western Tasmania, and the South Coast to Great Southern districts of Western Australia.

The northern Murray–Darling Basin soil moisture levels were mostly average in the east in response to the above average winter season rainfall, but below average in the west. Soil moisture was very much above average in some parts of the Namoi and Gwydir catchments. In the southern Murray–Darling Basin, soil moisture was average in most areas and above average in some areas in the east. Where soils are saturated further rainfall during the spring season may lead to large inflows into water storages.

  • Rainfall deficiencies for the period commencing April 2020 persist in Queensland
  • Accumulated rainfall deficits at multi-year timescales remain in many parts of Australia
  • Water storages continued to fill in the Murray–Darling Basin during the winter season
  • South East and Central Queensland storages remain low

Storage levels in the Murray–Darling Basin continued to increase significantly

The total water storage (accessible) in the Murray–Darling Basin continued to increase and reached 86.1% of capacity at the beginning of the spring season; an increase of 3.7% of capacity over the last month. Compared to the same time last year, when the total storage volume was only 57.6%, the water storages are in a significantly better position.

In the New South Wales part of the northern Basin, the winter filling season was relatively wet. However, that filling rate has slowed down during the first month of spring but continued. The total storage in the northern Basin increased by 1.4% to 81.8% of capacity (3 800 GL) at the end of September. This is the highest level since March 2012 and is significantly higher than the same time last year when it was only 26%.

In the northern Basin, the biggest change in storage during the month were for Chinchilla Weir (−12%), Lake Fyans (−9.5%), and Jack Taylor Weir (−9.5%). In the northern Basin, some storages (Pindari, Chaffey, Keepit, and Coolmunda) are at or near their full accessible capacities. Despite this, other storages including Split Rock, Windamere, and Cooby Creek are less than 50% full.

The total storage in the southern Basin increased by 4.3% to 87.1% (20 662 GL) in September. This is considerably higher than the same time last year when it was only 64.6%. Several storages in the southern Basin are at or near full accessible capacity (Lake Nillahcootie, Googong, Wyangala, Bendora, Corin, Cotter, Lauriston, Malmsbury, and Upper Coliban). All three of the very large storages in the southern Basin (Hume, Dartmouth, and Eildon) continued to increase this month. Hume has increased by a further 2.8%, bringing it to 96% of capacity, the highest level since November 2016. In September, the dam was operated in controlled release mode to create airspace and prevent the dam from spilling. With predictions of above median rainfall in spring, there is a possibility of Hume dam spilling in coming weeks.

The Menindee Lakes system has seen a period of rapid filling since April 2021 to reach 113% of accessible capacity (spilling) in September. 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 December 2012; significantly higher than the same time last year when it was only 27.2% full.

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

Major storage levels in the Murray-Darling Basin
Major storage levels in the Murray–Darling Basin
MDB south storage levels
MDB south storage levels
MDB north storage levels
MDB north storage levels

South East Queensland storages continue to remain low

In South East Queensland, the largest storage, Wivenhoe, decreased in September, falling to 40.5% of capacity, due to below average rainfall during the month. This is lower than the same time last year when it was 43. 9% and continues the significant decreases of the past three years.

The water levels of the two large rural systems in South East and Central Queensland, Bundaberg and Nogoa Mackenzie, remained low. The accessible volume of the Bundaberg system dropped further in September to 29.8% of capacity, the lowest level in more than ten years, and significantly lower than the same time last year when it was 49.2%. By the end of September 2021, the storage levels in the Nogoa Mackenzie system dropped to 14.5%, slightly higher than 10.3% of storage at the same time last year.

Product code: IDCKGD0AR0

A very dry month for the southeastern mainland increases rainfall deficiencies
Read details...

Soil moisture data is from the Bureau's Australian Water Resources Assessment Landscape (AWRA-L) model, developed through the Water Information Research and Development Alliance between the Bureau and CSIRO.
See: Australian Landscape Water Balance.

This section displays rainfall maps. Current drought status is described in the previous section. For historical drought status statements, go to archive of drought statements

Also available at Maps – recent conditions

Creative Commons By Attribution logo Unless otherwise noted, all maps, graphs and diagrams in this page are licensed under the Creative Commons Attribution Australia Licence