A very dry month for the southeastern mainland increases rainfall deficiencies
Soil moisture details are reported when there are periods of significant rainfall deficits.
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.
What is drought?
Drought is a prolonged, abnormally dry period when the amount of available water is insufficient to meet our normal use. Drought is not simply low rainfall; if it was, much of inland Australia would be in almost perpetual drought. Because people use water in so many different ways, there is no universal definition of drought. Meteorologists monitor the extent and severity of drought in terms of rainfall deficiencies. Agriculturalists rate the impact on primary industries, hydrologists compare ground water levels, and sociologists define it by social expectations and perceptions.
It is generally difficult to compare one drought to another, since each drought differs in the seasonality, location, spatial extent and duration of the associated rainfall deficiencies. Additionally, each drought is accompanied by varying temperatures and soil moisture deficits.
Rainfall averages, variability and trends
- Average rainfall: How much rain do you expect?
- Rainfall variability: How consistent is rainfall in your area?
- Rainfall history: Check tables, graphs and data from your local weather station.
- Rainfall trends: Has your rainfall changed?
Lowest on record - lowest since at least 1900 when the data analysed begin.
Severe deficiency - rainfalls in the lowest 5% of historical totals.
Serious deficiency - rainfalls in the lowest 10% of historical totals, but not in the lowest 5%.
Very much below average - rainfalls in the lowest 10% of historical totals.
Below average - rainfalls in the lowest 30% of historical totals, but not in the lowest 10%.
Average - rainfalls in the middle 40% of historical totals.
Above average - rainfalls in the highest 30% of historical totals, but not in the highest 10%.
Very much above average - rainfalls in the highest 10% of historical totals.
Australian Government drought assistance
Department of Agriculture and Water Resources information and contacts:
- Water Information
Water resources assessments and forecasts
- Water and the Land
Weather and climate for primary industries
- Australian Bureau of Agricultural and Resource Economics and Sciences
(ABARES) is a research bureau within the Department of Agriculture, Fisheries and Forestry aimed at Australia's primary industries.
- Climate Change in Australia
Bureau/CSIRO website, including rainfall and temperature projections and impacts for the coming decades.
- CSIRO-BoM Drought-EC Report (July 2008)
An assessment of the impact of climate change on the nature and frequency of exceptional climatic events, and accompanying Supplementary Information.
Deficiencies persist in many areas, but ease somewhat in the southeast
December rainfall was above average for coastal northern Queensland, largely as a result of tropical cyclone activity, and an active monsoon trough across the Coral Sea towards end of the month. Rainfall was also above average for much of Victoria and adjacent southwest New South Wales and border regions of South Australia. Further west, a large area spanning southeastern Western Australia and northwestern South Australia also had above average rainfall.
Rainfall for December was below average across much of Queensland away from the east coast, northern New South Wales, northeastern to central southern South Australia, across the Northern Territory, and across much of northern and the inland west of Western Australia.
Rainfall deficiencies for periods up to 12 months have eased across much of Victoria and parts of southern New South Wales, but have increased somewhat further north. At the longer 21-month timescale deficiencies remain generally similar, but have increased in some parts of northern New South Wales.
Rainfall for 2018 as a whole was exceptionally low over the southeastern quarter of the mainland, with much of the region experiencing totals in the lowest 10% of records. Significant rainfall deficiencies continue to affect large areas of eastern Australia at timescales out to around two years' duration. Annual rainfall was the seventh-lowest on record (since 1900) for the Murray-Darling Basin.
The year was very warm, and exceptionally so in December. Mean monthly temperature for December was the warmest on record for Australia, with prolonged periods of extreme heat, especially late in the month. Very warm temperatures across eastern Australia in the vast majority of months for the past two years have increased moisture stress, adding to the impact of low rainfall.
9-month rainfall deficiencies
Rainfall was below average across much of Australia for the seven months from April to October 2018, generally near average for November across large parts of the southeast and southwest, and above average for parts of the mainland southeast, focused on western Victoria in December.
Southern Australia receives the bulk of its rainfall between April and November (the southern wet season), so rainfall deficiencies during this period are particularly significant. The occurrence of high rainfall after the end of the main agricultural and runoff season has the effect of reducing rainfall deficiencies, but does not fully ameliorate the impact of earlier dry conditions.
Despite recent rainfall, serious or severe rainfall deficiencies persist across much of the eastern mainland, although deficiencies have decreased in northern Victoria and southern New South Wales.
In northern New South Wales, adjacent northeastern South Australia, and much of Queensland rainfall deficiencies have increased. Deficiencies have also increased in the Kimberley in Western Australia and have emerged across the northern Alice Springs District in the Northern Territory.
Large areas of serious or severe rainfall deficiencies are in place in East and West Gippsland in Victoria; areas of eastern South Australia between the Murraylands District and the northeast; large areas of northern New South Wales away from the coast, and an area in the South West Slopes and Riverina districts; large areas of Queensland away from the west and the east of the State; a small area of Western Australia in the Southeast Coastal District and large areas in the northeast of the Interior District and southern and coastal Kimberley; and in the north of the Alice Springs District in the Northern Territory.
12-month rainfall deficiencies
For the 12-month period, rainfall deficiencies have decreased across most of Victoria and southwestern New South Wales, and have increased in severity across much of the remainder of New South Wales, northeastern South Australia, and southwestern Queensland.
Serious or severe rainfall deficiencies persist in the eastern half of South Australia except the far southeast and far northeast; most of Gippsland and far northwestern Victoria; most of New South Wales away from the coastal strip; southwestern Queensland and the Warrego District, in the Central Highlands and Coalfields, and in pockets on the Central Coast and along the southern border of Queensland inland of the ranges; and in Western Australia's South Coastal District. Since last month, small pockets of deficiencies have also emerged across the north of the Alice Springs District in the Northern Territory.
21-month rainfall deficiencies
The effect of December rainfall on deficiencies at longer timescales has generally been very small, and deficiencies for the period starting in April 2017 have increased in the northern half of New South Wales and in parts of central and southern Queensland.
Serious or severe rainfall deficiencies continue across most of New South Wales excluding the northeast to central coast and southern regions inland of the coastal ranges; across Gippsland in Victoria; areas of coastal eastern and northern Tasmania; much of the eastern half of South Australia away from the far southeast and far northeast;much of the southern half of Qld away from the coastal ranges.
Deficiencies also persist in Western Australia along the coast between the Pilbara and the South West, and in the South Coastal District.
December rainfall has increased relative lower-layer soil moisture (from 10 cm to 100 cm deep) over southeastern Australia, and much of northeastern Queensland. Conversely, soil moisture values have decreased over much of the western half of Australia, and in greater southeastern Queensland.
Soil moisture for December was below average for much of Gippsland in eastern Victoria; large parts of northern New South Wales, extending into adjacent southern Queensland, and also in the Central Highlands and Coalfields District in Queensland; northwestern Queensland and parts of the northeastern Northern Territory; along the coast between Western Australia's Pilbara and the central Top End coast in the Northern Territory; and also across much of South West Western Australia.
Soil moisture was above average for a band through Western Australia from around Carnarvon extending east to take in much of Central Australia, in large areas along the coast of South Australia, in northwestern Victoria and adjacent southwestern New South Wales, across much of Cape York Peninsula and the tropical to central coast of Queensland, an area about the southeast of the Top End in the Northern Territory, and northeastern Tasmania.
Please note: the map displayed here is produced using AWRA-L v5, and may differ slightly to that shown on the Australian Landscape Water Balance page, which has recently transitioned to the AWRA-L v6 model. The Drought Statement will shortly move to AWRA-L v6 also.
- December rainfall below average for much of northern Australia, southern Queensland, northern New South Wales, and northeastern to central South Australia
- Rainfall above average for December across northern coastal Queensland, parts of the mainland southeast (particularly western Victoria), and an area of southeastern Western Australia and northwestern South Australia
- Rainfall deficiencies decreased at the 9- and 12-month timescales in parts of the southeast, but increased in northern Australia
- Longer-term deficiencies continue with generally little change in most areas
- Lower-level soil moisture below average for December across coastal north and southwest of Western Australia, large parts of northern New South Wales, large areas in inland southeastern and central northern Queensland, and parts of Top End and northeast Northern Territory
- Record high temperatures added to moisture stress
Product code: IDCKGD0AR0