Drought
Rainfall deficiencies and water availability

Very much below average rainfall in parts of the south

Rainfall was below average to very much below average (in the lowest 10% of Augusts since 1900) for:

• Victoria, southern South Australia and southern and part of western New South Wales
• areas in the south of the Northern Territory into South Australia and south-western Queensland
• an inland area in the south-west and along the south-east coast of Western Australia.

Rainfall was above average to very much above average (in the highest 10% of Augusts since 1900) for:

• much of western Tasmania
• a band extending from the Gascoyne region of Western Australia into the Northern Territory and South Australia
• some coastal areas in south-west of Western Australia
• much of eastern Queensland and areas in north-east New South Wales.

Victoria had its driest August since 2014, 55.4% below the 1961–1990 average.

Monitoring of rainfall deficiencies since May 2023 has ended. Deficiencies from August 2023 impact similar regions to the longer period and continue to be monitored.

Long-range forecast

The long-range forecast released on 5 September 2024, indicates that for September to November

• rainfall is likely (60 to 80% chance) to be above average for large parts of the eastern half of Australia
• rainfall is likely to be within the typical seasonal range for the western half of Australia and Tasmania.

October is the start of the northern wet season. During September to November, conditions across most of northern Australia are expected to shift from dry to wet.

Long-term trends

State of the Climate 2022 reported a shift towards drier conditions across the south-west and south-east of Australia, particularly during the cool season months of April to October. There has been a decline of around 16% in April to October rainfall in the south-west of Australia between 1970 and 2023, and around 9% in the south-east since the late 1990s. This is due to a combination of natural variability on decadal timescales and changes in large-scale circulation caused by an increase in greenhouse gas emissions.

Deficiencies for the 7 months since February 2024

For the 7-month period since February 2024, areas with lowest on record, severe or serious rainfall deficiencies (record low rainfall totals or in the lowest 5% or 10% of periods, respectively, since 1900) extend along:

• a small area around Albany in south-west Western Australia
• agricultural regions of South Australia into western Victoria
• coastal South Gippsland in Victoria and north-eastern ranges into southern New South Wales
• coastal western Tasmania and Bass Strait islands.

Areas with lowest on record rainfall include parts of the Eyre Peninsula, York Peninsula and the agricultural regions of South Australia, and across western Victoria along the coast to South Gippsland.

Compared to July, in western Tasmania and south-west Western Australia rainfall deficiency regions have reduced in size and severity, while in the south-eastern mainland states, deficiencies generally increased in extent and severity, particularly in Victoria, where lowest on record rainfall areas extended across most of the south-west and deficiency regions expanded in Gippsland and the along the ranges.

Deficiencies for the 13 months since August 2023

For the 13-month period since August 2023, areas with lowest on record, severe or serious rainfall deficiencies (record low rainfall totals or in the lowest 5% or 10% of periods, respectively, since 1900) extend along:

• coastal margins of the north-west, an area of Pilbara and Gascoyne, and across the south-west of Western Australia
• agricultural regions of South Australia, south-west Victoria and much of Tasmania, including areas with lowest on record rainfall along the south-east coast of South Australia and south-west Victoria.

Compared with July, in Western Australia rainfall deficiencies reduced in severity across the south-west. For south-eastern Australia, rainfall deficiency areas expanded further inland in South Australia and western Victoria and contracted in Tasmania.

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Below average soil moisture in the south

August soil moisture deficiencies continue in the south of the country, with below to very much below average soil moisture in:

• parts of south-east Western Australia
• southern South Australia
• most of Victoria into southern New South Wales
• central Tasmania.

August brought above average rainfall across the south-west of the country and eased soil moisture deficiencies. Above average rainfall for August also eased soil moisture deficiencies in western Tasmania.

However, rainfall was very much below the August average in south-eastern Australia, intensifying soil moisture deficiencies in that area.

Agriculture in southern Australia relies on higher cool season soil moisture. Low soil moisture for long periods of time affects crop growth and is an indicator of agricultural drought.

Severe evaporative stress in large areas of southern Australia

Evaporative stress for the 4 weeks ending 31 August 2024 was elevated (negative Evaporative Stress Index (ESI)) in:

• parts of south-east, inland and northern Western Australia
• southern South Australia.
• most of Victoria into southern New South Wales
• much of inland Queensland and Northern Territory.

While vegetation moisture stress lessened in south-west Western Australia and western Tasmania in August compared with July, significantly elevated ESI values (less than −2) persisted and expanded over a larger area of mainland south-eastern Australia.

The ESI represents the influence of a combination of meteorological and land factors on drought conditions. A negative ESI indicates vegetation moisture stress linked to agricultural and ecological drought.

See this journal publication for further details on calculation and use of the ESI in drought monitoring.

Rainfall deficiencies and water shortage at the end of August

• August rainfall was below average for Victoria; southern South Australia; southern and western New South Wales; areas in the south of the Northern Territory and south-western Queensland; an inland area in the south-west and the south-east coast of Western Australia.
• Recent rainfall deficiencies eased in August across south-west Western Australia and western Tasmania but remain severe across the agricultural regions in South Australia, in western and southern Victoria and north-eastern ranges into southern New South Wales.
• Longer-term serious to severe rainfall deficiencies persist in areas of south-west and north-west Western Australia, across agricultural regions of South Australia, south-west Victoria and much of Tasmania.
• Soil moisture remains below average in the south-east but deficiencies have eased in the south-west and western Tasmania.
• Streamflow was low at a large proportion of sites in Victoria and the southern Murray–Darling Basin.
• Most water storage levels were low in the west of Western Australia, some storages were low in central Queensland and in south-eastern states, many storages were 10 to 50% lower than the time last year.

Low streamflow in the Victoria and south-east Murray–Darling Basin

In August, higher than average (based on records since 1975) streamflow was observed at 38% of the 864 sites with available data. These were mostly in eastern and northern Australia, including scattered sites in the west of Western Australian where soil moisture was already high. Very much above average streamflow (highest 10% of years since 1975) was observed at 15% of sites, including 5% of sites with highest on record, mainly in Northern Territory and Queensland.

Lower than average streamflow was observed in August at 25% of sites. These were mostly associated with below average rainfall and dry catchment conditions. These were observed in:

• Victoria and South Australia
• north-east Tasmania
• the southern Murray–Darling Basin
• scattered sites in north Queensland
• scattered sites in south-west and north-west of Western Australia.

Very much below average streamflow (lowest 10% of years since 1975) was observed at 10% of sites, including 2% of sites with lowest on record, mainly in Victoria, southern Murray–Darling Basin, scattered sites in north Queensland and south-west of Western Australia.

Streamflow was average at 38% of sites, across Australia.

Low storage levels in the west of Western Australia, Southern Australia and Central Queensland

By the end of August, the total water storage in Australia (across 306 public storages) was at 75.5% of capacity, slightly higher (by 1.6%) than the previous month, and slightly lower than at the same time last year (by 3.1%). Despite Australia's overall high storage, volumes decreased in August for 101 public storages. Some storages were relatively low in several regions including:

• central Queensland
• the northern and southern Murray–Darling Basin
• south-east of New South Wales
• western Victoria
• South Australian Gulf drainage division
• central Tasmania
• urban areas of Perth in Western Australia.

The storage volume decreases were generally in regions that had below average rainfall and dry catchment conditions during August.

Combined storages in the Murray–Darling Basin were 82.4% full at the end of August, a 2.1% increase from July and a 10.8% decrease from the same time last year. Menindee Lakes, in the west of New South Wales was 59.8% full at the end of August, slightly decreased from July and a 19.9% decrease from the same time last year. The combined storages in the Wimmera–Mallee system of Victoria were just above half full (54.9% of its capacity) at the end of August, mainly due to the below average rainfall in during March to June and August.

Above average August rainfall across south-west of Western Australia resulted in an increase in some storage levels. Perth's surface water storages were 44.7% full at the end of August, a 6.2% increase from July, and a 6.9% decrease from the same time last year. Long-term declines in surface water inflows to Perth's storages means the city's water supply is reliant on desalination and groundwater sources.

The Harding storage in the Pilbara–Gascoyne drainage division was at 27.8% of capacity at the end of August, a 1.2% decrease from July and a 29.8% decrease from same time last year.

In central Queensland, water storage in Fairbairn was at 34.7% of capacity, a 0.4% increase from July and a 1.9% decrease from same time last year. Water levels in the Lake Awoonga in south-eastern Queensland remain low (41.2% full), at the end of August, a 1.8% decrease from July and a 8.0% decrease from the same time last year.

Water storage in Great Lake in central-northern Tasmania, the second largest by capacity in the state, was 28.4% full at the end of the month, a 3.3% increase from July but a 8.7% decrease from the same time last year.