Drought
Rainfall deficiencies and water availability

Deficiencies continue in western Tasmania following very much below average January rainfall

February rainfall was below average for much of eastern and southern Queensland, New South Wales extending into adjacent eastern South Australia, most of northern and eastern Victoria, the South West Land Division and much of the interior of Western Australia, extending to the Nullarbor coast and coastal South Australia.

Areas of above or very much above average February rainfall were mostly in the north of Australia, and isolated pockets in the south-west Pilbara, and the Western District in Victoria.

For the 3-month period since December 2022, serious deficiencies (totals in the lowest 10% since 1900) have emerged in south-west Western Australia, south-east Queensland, areas of north-east New South Wales, parts of the Wimmera in Victoria, and in western Tasmania.

For the 15-month period starting December 2021, areas of serious rainfall deficiencies have grown in western Tasmania and continued in parts of south-west Western Australia.

The long-range forecast released on 2 March 2023 indicates that for March to May, below median rainfall is likely (60 to 80% chance) for most of Australia away from the south-east coast. Autumn maximum temperatures are likely to above average across much of the country and minimum temperatures likely to be warmer in coastal parts but cooler in parts of the interior.

State of the Climate 2022 reported that there has been a shift towards drier conditions across the south-west and south-east Australia, especially for the cool season months of April to October. In 19 of the 23 years from 2000, April to October rainfall in southern Australia has been below the 1961–1990 average. Of the four years with above-average cool season rainfall in southern Australia from 2000, three (2010, 2016 and 2022) were during La Niña events or had a strong negative Indian Ocean Dipole, favourable for wetter than usual conditions across Australia.

Deficiencies for the 3 months since December 2022

Summer 2022–23 rainfall was below average for large areas in the south of Western Australia, in Tasmania, Victoria, north-eastern New South Wales and the south-eastern quarter of Queensland.

For the 3-month period since December 2022, serious rainfall deficiencies (totals in the lowest 10% since 1900) have emerged in south-west Western Australia, with the South West and South Coastal districts mostly in severe deficiency (totals in the lowest 5% since 1900), and for areas along the far south-west coast rainfall was lowest on record.

In Queensland, a large area of severe rainfall deficiency extends from the Wide Bay and Burnett coast, across the south of the Central Highlands and Coalfields, along the east of the Maranoa and Warrego, and over much of the Darling Downs and Granite Belt districts. There are also pockets of serious and severe deficiency in adjoining areas of north-eastern New South Wales.

In the south-east of the country, Tasmania has serious deficiencies along the west with a large area of severe deficiency in the north-west. Areas of serious deficiency have also developed in the Victorian Wimmera.

Deficiencies for the 15 months since December 2021

For the 15-month period starting December 2021, serious rainfall deficiencies have continued in parts of south-west Western Australia and western Tasmania, where the area of severe deficiency has extended further inland compared to deficiencies over the 14-month period to January 2023. February rainfall was close to average in western Tasmania, but below to very much below average (driest 10% of all Februarys since 1900) in south-west Western Australia.

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Soil moisture

Root-zone soil moisture (soil moisture in the top 100 cm) remains below February average in south-eastern Queensland, areas of the north and coastal New South Wales, parts of the North East Pastoral District in South Australia, the south of Western Australia, Western Tasmania, and across central Victoria to South Gippsland. Compared to January, soil moisture has decreased in areas of south-eastern Queensland, much of Victoria and in Tasmania.

Evaporative stress

Evaporative stress for the 4 weeks ending 28 February 2023 has increased in intensity (index is negative) in south-eastern Queensland, across much of inland New South Wales, Victoria, Tasmania and central and south-west Western Australia. Evaporative stress has decreased (index is positive) over much of the Northern Territory and tropical Queensland which experienced heavy rain and cool temperatures during February.

See the journal publication for further details on calculation and use of evaporative stress index in drought monitoring.

• February rainfall was below average in areas in all states and Territories.
• Over the last 3 months, since December 2022, serious rainfall deficiencies (totals in the lowest 10% of observations since 1900) have developed in south-east Queensland, north-east New South Wales, south-west Western Australia, parts of the Wimmera in Victoria, and western Tasmania.
• Soil moisture remains below average in south-east Queensland, south-west Western Australia, western Tasmania, Victoria and north-east South Australia.
• Low streamflows were recorded in south-west Western Australia, inland and south-eastern Queensland, and north-eastern New South Wales.
• Low storage levels continue in some parts of central Queensland, central Tasmania, south-east New South Wales and some urban storages for Perth in Western Australia.
• For autumn, below median rainfall and above average temperatures are likely for most of Australia away from the south-east coast.

Streamflows low in south-eastern and south-western Australia and high in the north-east

In February, streamflows were average at 49% of sites (based on records since 1975), spread across the country. Lower than average streamflows were observed at 15% of the 858 sites, mostly associated with below average rainfall and drier catchment conditions in south-west and central Western Australia, north-west Tasmania, inland and south-eastern Queensland, north-eastern and central New South Wales.

In February, above to very much above average streamflows were observed in 36% of sites, mainly in the south-central and eastern areas of Murray–Darling Basin, Victoria, the Kimberley region in Western Australia, and northern tropics of Queensland. In the Murray–Darling Basin, despite average to below average rainfall, streamflows were high in southern areas due to flow from upstream catchments from flooding in recent months.

Overall high storage levels across the country with a few pockets of low storage levels

In February, areas in Northern Territory and north-east Queensland, received above average to very much above average rainfall. These resulted in a slight increase in some storage levels from January, particularly in north-east Queensland, the Northern Territory and north-west of Western Australia. By the end of February, the total water storage volume in Australia (across Australia's 306 public storages) was 79.6% of full capacity; slightly higher than the previous month and higher than at the same time last year. The combined storages in the Murray–Darling Basin were 91.5% full, up from 89.7% at the same time last year. Despite most of the major storages being at high levels, there remain several pockets of low storage volumes: particularly in central Queensland, central Tasmania, and south-east New South Wales, western Victoria and some urban storages for Perth.

Perth's surface water storages were close to half capacity at the end of February at 49.8% (0.8% less than this time last year). However, with the long-term decline of surface water inflows into storages, the city's water supply is generally more reliant on desalination and groundwater sources than surface water.

With drier catchment conditions across western Tasmania in previous months, storage volumes in Tasmania remain around half of full capacity (51.7%) which is lower (1.6%) than last month and also lower than at the same time last year.

Water levels in the Nogoa Mackenzie system in central Queensland remain low despite increasing to 45.3% by the end of February (up from 23% at the same time last year). In central Queensland, water storage in Fairbairn was below half capacity at the end of February at 44.6% (up from 21.9% at the same time last year).