Dry in the south and across much of inland Australia

The national, area-averaged rainfall total in April was 26.0% below the 1961–1990 average. Rainfall was below average for western, southern and central parts of the country and above in Australia's east and north. It was the eighth-driest April on record for the South Australia, with area-averaged rainfall 86.4% below average.

Rainfall was below average to very much below average (in the lowest 10% of Aprils since 1900) for a large area of Western Australia including all of the south-west and much of the interior and the Kimberley, most of South Australia, southern Northern Territory, western and southern Tasmania, and parts of western Victoria, north-western New South Wales and central Queensland. April rainfall was the lowest on record for isolated pockets of Western Australia's south-west coast.

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 15 per cent in April to October rainfall in the south-west of Australia since 1970. 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.

May is the beginning of the dry season in northern Australia, and rainfall is usually low through to the start of the wet season in October.

The long-range forecast released on May 2024, indicates that for May, rainfall is likely to be below median for most of Australia, shifting to close to equal chances of above or below median rainfall in June.

Most of Australia away from the north-east and east has an increased likelihood of unusually low rainfall for May. Unusually low rainfall is defined as the driest 20% of May periods from 1981 to 2018.

Rainfall averaged across the 3 months May to July is likely to be below median for parts of southern, eastern, and northern Australia, dominated by the below median rainfall forecast for May.

For May to July, parts of south-eastern Australia, northern Tasmania and eastern Queensland have an increased likelihood of unusually low rainfall.

May to July rainfall has about equal chances of being above or below median for the west of Western Australia, the south of the Northern Territory, most of South Australia, southern Queensland away from the east, and parts of western New South Wales.

Deficiencies for the 9 months since August 2023

For the 9-month period since August 2023, areas with severe or serious rainfall deficiencies (rainfall totals in the lowest 5% or 10% of periods, respectively, since 1900) extend along the coast of south-west Western Australia, including large areas with lowest on record rainfall. Deficiency areas also extend along parts of the north-west coast and inland from south-west of the Pilbara into the Gascoyne district. Rainfall deficiency areas generally expanded further inland and increased in severity in the south-west during April.

Deficiencies for the 12 months since May 2023

For the 12-month period since May 2023, areas of severe or serious rainfall deficiencies (rainfall totals in the lowest 5% or 10% of periods, respectively, since 1900) extend across much of the west of Western Australia, and along the Pilbara and south-west Kimberley coast. There were large areas of lowest on record rainfall in inland areas of the Pilbara and Gascoyne districts, from Perth to Geraldton along the coast, for much of the far south-west, and a small area inland of Esperance. During April, the extent and severity of deficiency areas increased in the south of the state.

In the east of the country, there are small areas of rainfall deficiency in southern South Australia, south-west Victoria, and northern and eastern Tasmania. April rainfall cleared most areas of deficiency in north-eastern New South Wales.

Deficiencies for the 17 months since December 2022

For the 17-month period since December 2022, areas with severe or serious rainfall deficiencies (rainfall totals in the lowest 5% or 10% of periods, respectively, since 1900) include coastal Western Australia between Port Hedland and Cape Leeuwin, and inland areas in the south-west. Areas of lowest on record rainfall for the 17-month period extend inland from Perth to north of Geraldton, and for much of the far south-west.

April rainfall in eastern Australia mostly cleared 17-month rainfall deficiency areas in Queensland, and in New South Wales except for parts of the north coast. However in parts of coastal Tasmania and isolated pockets of South Australia the extent of severe rainfall deficiencies expanded.

NULL

Below average soil moisture in the south

With continued very low rainfall in April, root zone (0–1 m depth) soil moisture was below average for much of south-west Western Australia, southern South Australia and Tasmania. Parts of far south-west Western Australia experienced the lowest soil moisture on record for this time of year (based on all years since 1911). Compared with March, areas of very much below average soil moisture expanded over southern Western Australia and southern South Australia. During cropping season, prolonged low root zone soil moisture limits crop growth and is an indicator of agricultural drought.

Despite close to average rainfall conditions over parts of the Northern Territory during April, higher than average soil moisture continued from March due to already wet soils and lower than average temperatures. Soil moisture was average to very much above average across northern and eastern Australia.

Soil moisture increased over south-east Queensland, New South Wales and western and central Victoria following high rainfall in April. However, soils remain relatively dry in the far south-west of Victoria.

Increased evaporative stress in the south-west

Evaporative stress for the 4 weeks ending 30 April 2024 was elevated (negative Evaporative Stress Index (ESI)) for most of the west of Western Australia and the southern half of South Australia as well as parts of western New South Wales and the Queensland central coast. Notably, April rainfall eased evaporative stress in south-east Queensland, north-east New South Wales, Victoria and Tasmania, while a lack of rainfall and higher than average maximum temperatures continued to intensify the ESI in south-west Western Australia.

The ESI is the standardised anomaly of the ratio of actual evapotranspiration to potential evapotranspiration and represents the influence of a combination of meteorological and land factors on drought conditions. A negative ESI is an indicator of vegetation moisture stress associated with agricultural and ecological drought. See this journal publication for further details on calculation and use of the ESI in drought monitoring.

  • Rainfall in April was below average for western, southern and central parts of the country and the eighth-driest April on record for South Australia.
  • For the 9 months since August 2023, large areas with rainfall deficiencies have intensified in the west of Western Australia. In eastern Australia, small deficiency areas have expanded and intensified in south-eastern South Australia, south-western Victoria and much of Tasmania. Areas of longer term, 12 to 17 months, rainfall deficiencies, cover much of the west of Western Australia, with small areas in eastern states, particularly Tasmania.
  • April soil moisture was lowest on record in the far south-west of Western Australia and areas of very much below average soil moisture expanded in southern Western Australia and southern South Australia.
  • Low streamflow was observed in April at widespread sites in Western Australia in the south-west and the Pilbara–Gascoyne catchment area, in Tasmania, and in scattered sites on the eastern mainland.
  • Storage levels remain low in some storages in central Queensland and many storages across New South Wales, central Tasmania, western Victoria, South Australia, and for Perth and the Pilbara–Gascoyne catchment area in Western Australia.

Low streamflow in Tasmania and the west of Western Australia, high flows in northern and central eastern Australia

Below to very much below average streamflow (based on records since 1975) during April was observed at 19% of the 655 sites with available data, mostly associated with below average rainfall and dry catchment conditions. Below average streamflow was particularly widespread in Western Australia in the south-west, the Pilbara–Gascoyne catchment area, and in Tasmania, with scattered sites in central Queensland, in the south of New South Wales, western Victoria and South Australia. Very much below average streamflow was observed at 3% of sites, mainly in Tasmania and south-west Western Australia.

Streamflow was average at 36% of sites, across eastern and south-eastern Australia and scattered sites in Western Australia.

Above to very much above average streamflow was observed at 45% of sites in northern Australia, south-east Queensland, some sites in eastern New South Wales and central Victoria, mostly due to heavy rainfall and high antecedent soil moisture conditions in those catchments.

Very much above average streamflow was observed at 10% of sites, mainly in the Northern Territory, the Kimberley district in Western Australia, the northern wet tropics and southern Queensland and north and south-eastern New South Wales, mostly due to above average rainfall in these areas.

In April, moderate to major flood warnings were issued for rivers across parts of Queensland and New South Wales due to heavy rainfall into already saturated river catchments. Wet catchments and downstream movement of floodwater resulted in above average streamflow at sites in these areas.

Streamflow decile rankings across Australia
Streamflow conditions in April 2024

Low storage levels in the west and south and high in the north and east

In April, below average to very much below rainfall and dry catchments conditions across most of the South Australia and Western Australia, parts of southern Northern Territory, southern Tasmania, western Victoria, north-western New South Wales and central Queensland resulted in a slight decrease in some storage levels from March. By the end of April, the total water storage in Australia, across 306 public storages, was at 78.4% of capacity, slightly lower (by 2.4%) than the previous month, and slightly higher than at the same time last year (by 1.2%). Despite Australia's overall high storage, volumes decreased in April for 176 public storages and remain low in several locations, particularly in central Queensland, many storages across New South Wales, western Victoria, South Australia, central Tasmania, and in Western Australia for Perth and the Pilbara–Gascoyne catchment.

Major storage levels across Australia
Storage conditions in April 2024

Combined storages in the Murray–Darling Basin were 74.9% full at the end of April, a slight decrease by 1.5%, from March and 13.8% from the same time last year. Menindee Lakes, in the west of New South Wales was below half (44.5%) of its capacity at the end of April, a decrease of 3.6% from March and 35.2% from the same time last year.

Perth's surface water storages were 36.7% full at the end of April, a 1.6% decrease from March, and an 10.0% 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. Water storage in Pilbara–Gascoyne was at 33.6% of capacity at the end of April, a decrease of 1.7% from March and a decrease of 34.0% from same time last year.

Central eastern parts of Queensland received average to below average rainfall in April and some storages remained low in those areas. In central Queensland, water storage in Fairbairn was at 38.8% of capacity, a decrease of 1.6% from March and a slight decrease, by 3.7%, from same time last year. Water levels in the Lake Awoonga in south eastern Queensland remain low, capacity (53.8% full) at the end of April, a slight increase, by 0.4%, from March and a 6.9% decrease from the same time last year (60.7%).

Due to below average rainfall and dry catchment conditions since February, water storage in Great Lake in Tasmania decreased to 22.0% full by the end of the month, a 2.6% decrease from March and a 11.6% decrease from the same time last year.

Product code: IDCKGD0AR0

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.

Creative Commons By Attribution logo Unless otherwise noted, all maps, graphs and diagrams in this page are licensed under the Creative Commons Attribution 4.0 International Licence