Drought
Rainfall deficiencies and water availability

Below average rainfall in parts of the south, above average rainfall for much of the west and north-east

December rainfall was below average to very much below average (in the lowest 10% of Decembers since 1900) for:

• parts of south-western Western Australia
• parts of south-eastern South Australia and north-eastern New South Wales
• parts of eastern Victoria
• isolated areas in western Queensland and the central Northern Territory.

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

• most of Western Australia
• southern and northern parts of the Northern Territory
• parts of northern South Australia
• most of Tasmania
• large parts of Queensland and inland New South Wales
• isolated areas of Victoria.

Australia's area-averaged mean temperature in December was 1.88 °C above the 1961–1990 average, the third-warmest December on record for Australia since 1910 (following record warm Decembers in 2019 and 2018). Mean maximum temperatures were above to very much above average (in the highest 10% of all Decembers since 1910) for most of Australia.

December was the third month of the northern wet season and much of the north-west and north-east had above average rainfall. Most of the north has reached the northern rainfall onset threshold of 50 mm of rainfall since 1 September, with much of Queensland later than average and elsewhere generally earlier than average.

State of the Climate 2024 reported there has been a shift towards drier conditions across the south-west and south-east of Australia, especially during the cool season months of April to October. Across southern Australia (south of 26°S ) as a whole, since 1994, April to October rainfall has been above the 1961–1990 average in only 6 years. This is due to a combination of natural variability on decadal timescales and changes in large-scale circulation largely driven by an increase in greenhouse gas emissions.

The long-range forecast, released on 9 January 2025 for February to April 2025 shows:

• Rainfall is likely (60 to 80% chance) to be above average over most of northern and western Western Australia, most of the Northern Territory, northern and western Queensland and coastal parts of New South Wales and eastern Victoria, with highest chances over parts of Cape York Peninsula. Rainfall is likely to be below average for most of western Tasmania.
• Rainfall is likely to be within the typical range for the season for most remaining areas.
• There is an increased chance of unusually high rainfall for the central Northern Territory, northern and eastern Queensland and much of Western Australia.
• Above average maximum temperatures are likely to very likely (60% to greater than 80% chance) for most of eastern and southern Australia and across the Northern Territory's Top End.

Deficiencies for the 11 months since February 2024

For the 11-month period since February 2024, areas with severe or serious rainfall deficiencies (rainfall totals in the lowest 5% or 10% of periods, respectively, since 1900) extend along:

• small areas of the south coast of Western Australia
• agricultural regions of South Australia extending into western Victoria
• coastal areas of South Gippsland in Victoria and small areas of the eastern ranges into southern New South Wales
• coastal north-west Tasmania including King Island.

Areas with lowest on record rainfall include a region around Ceduna, and parts of the Eastern Eyre Peninsula, York Peninsula, Murraylands and Upper South East districts in South Australia.

Compared to November, areas of rainfall deficiency extended further inland in the south of Western Australia, but deficiency intensity eased along the coastal South Australia/Victoria border region and in south-eastern New South Wales.

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Below average soil moisture in parts of the southern and eastern mainland

December soil moisture was below to very much below average (in the lowest 10% of Decembers since 1900) in:

• the south of Western Australia excluding the far south-west and isolated pockets of northern Western Australia
• south-west South Australia and parts of the Eyre Peninsula extending to the greater Adelaide region
• much of southern Victoria, except the far south-west
• isolated pockets of eastern New South Wales
• isolated inland areas across Queensland and the Northern Territory.

December rainfall eased the severity and extent of long-term soil moisture deficiencies in the south-east, including most of Victoria, south-east New South Wales and Tasmania. Soil moisture deficiencies also eased in northern Queensland. Root-zone soil moisture across inland and western Australia is typically low at this time of year and the differences between above and below average can be relatively small.

Low soil moisture for long periods of time affects crop growth and can be an indicator of agricultural drought.

High evaporative stress continues in parts of southern mainland

Evaporative stress for the 4 weeks ending 30 December 2024 was elevated (negative Evaporative Stress Index (ESI)) in:

• southern mainland Australia
• parts of central inland Queensland
• the south-east of the Northern Territory.

Moisture stress decreased in most regions that had high ESI values in November, particularly in south-western Victoria and along the southern coast of south-west Western Australia, where the ESI had been significantly elevated (below −2).

The ESI represents the anomaly of the ratio of actual evapotranspiration to potential evapotranspiration standardised for the time of year. A lower ratio indicates higher vegetation moisture stress due to limited water availability and can be an indicator of 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 December

• December rainfall was below average for parts of south-western Western Australia; south-eastern South Australia; eastern Victoria; north-eastern New South Wales and parts of inland northern Australia.
• Recent rainfall deficiency areas extended further inland in the south-west of Western Australia but reduced in intensity in some parts of coastal South Australia and Victoria.
• Soil moisture remains below average in southern mainland Australia, but with an easing in the intensification of deficiencies in the south-east.
• Streamflow was low at a large number of sites in southern mainland, eastern Tasmania, and scattered sites in Queensland.
• Some water storage levels were low in the south-west of Western Australia and in central Queensland and many storages in south-eastern states, were 10 to 50% lower than the same time last year.

Low streamflow in southern Australia and central Queensland

In December, higher than average (based on records since 1975) streamflow was observed at 41% of the 883 sites with available data. These were mostly in the north, north-west and eastern Australia. December streamflow was average at 38% of sites, spread across Australia. Very much above average streamflow (highest 10% of years since 1975) was observed at 17% of sites, including 1% of sites with highest on record, across:

• the north of the Northern Territory
• the north-west of Western Australia
• south-eastern and northern areas of Queensland
• the inland areas of New South Wales
• Northern and eastern Tasmania.

This was due to above average rainfall and wet catchment conditions in those regions.

Lower than average streamflow was observed in December at 22% of sites. These were mostly associated with below average rainfall and dry catchment conditions. These were observed in:

• the South East Coast Victoria drainage division (43% of 101 sites)
• the South Australian Gulf drainage division (80% of 10 sites)
• central and northern areas of the North East Coast drainage division (8% of 148 sites)
• the Murray–Darling Basin drainage division (15% of the 329 sites)
• South West Coast drainage division (62% of 75 sites)
• Tasmania (15% of 21 sites).

Very much below average streamflow (lowest 10% of years since 1975) was observed at 4% of sites, mainly in western Victoria, South Australia, few sites in the south of Murray–Darling Basin, scattered sites in the Queensland, east of Tasmania and the south-west of Western Australia.

Low storage levels in the west of Western Australia, southern Australia and central Queensland

By the end of December, the total water storage in Australia (across 306 public storages) was at 72.8% of capacity, slightly higher (by 1.0%) than the previous month, and 1.7% lower than at the same time last year. Despite Australia's overall high storage, volumes decreased in December for 173 public storages. Some storages were relatively low in several regions including:

• central Queensland
• the southern Murray–Darling Basin
• Victoria, mostly in the west and far east
• south-east South Australia
• west and central Tasmania
• urban areas of Perth and in the Pilbara–Gascoyne in Western Australia.

The decrease in storage volumes were generally in regions that had dry catchment conditions during December.

Combined storages in the Murray–Darling Basin were 71.6% full at the end of December, a 2.1% decrease from November and a 13.8% decrease from the same time last year.

Menindee Lakes, in the west of New South Wales was 33.0% full at the end of December, a decrease of 4.2% from November and a 26.4% decrease from the same time last year. The combined storages in the Wimmera–Mallee system of Victoria were at 47.9% of capacity at the end of December, a decrease of 3.5% from November and a 19.9% decrease from the same time last year, mainly due to severe rainfall deficiencies since February 2024. Water storage in the Hume dam was at 53.4% of capacity at the end of December, a 2.2% decrease from November and a 31.6% decrease from the same time last year.

Perth's surface water storages were 45.4% full at the end of December, a slight (0.1%) decrease from November, and a 0.7% 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 19.7% of capacity at the end of December, a 1.8% decrease from November and a 22.2% decrease from the same time last year.

In central Queensland, water storage in Fairbairn was at 23.2% of capacity at the end of December, a 2.9% decrease from November and a 5.0% decrease from the same time last year. Water levels in Lake Awoonga in south-eastern Queensland remain low (37.1% full), at the end of December, a 1.0% decrease from November and a 9.2% 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 33.0% full at the end of the month. Inflow from rainfall resulted in a 1.0% increase from November and an increase of 1.7% from the same time last year.