Rainfall deficiencies increase for the east after drier than average June
June rainfall was below average for the Kimberley and the southwestern quarter of Western Australia, most of the Northern Territory, and large parts of South Australia, New South Wales, and Queensland. Rainfall for the month was in the lowest 10% of historical observations (decile 1) for some parts of the eastern mainland, with the largest area of decile 1 rainfall observed in the North West Slopes and Plains and Northern Tablelands districts inland of the Great Dividing Range in northeastern New South Wales.
Above average June rainfall over the northwest of Western Australia has alleviated deficiencies in the coastal southeast of the Pilbara and northeastern Gascoyne. Elsewhere, deficiencies persist, and have increased over large parts of eastern Australia and agricultural South Australia at both the 6- and 15-month timescales.
A dry start to the southern wet season
The start of the southern wet season has been drier than average. The southern wet season spans April to November, and corresponds to the southern agricultural cropping season. The start to the wet season has been particularly dry for the south of Western Australia, with some areas along Western Australia's southern coast receiving record-low rainfall for April to June. Decile 1 rainfall for the period was observed across large areas of southern Western Australia, New South Wales and southern Queensland, and Central Australia. For Australia as a whole, April to June 2018 has been the fourth-driest such period since comparable records commence in 1900.
These shorter-period deficiencies have occurred against the background of existing rainfall deficiencies, including at 6- and 15-month timescales, and will continue to be closely monitored by the Bureau as the southern wet season progresses.
6-month rainfall deficiencies
Below average rainfall for June has increased rainfall deficiencies across much of New South Wales, far southwestern Queensland, northeastern South Australia, and agricultural districts of South Australia between the Fleurieu and Eyre peninsulas. Serious to severe rainfall deficiencies also persist in southeastern South Australia and western to Northern Country Victoria, parts of Gippsland in Victoria, an area of the Central Highlands and Coalfields District in Queensland, and in Western Australia's South Coastal District and a small area north of Kalbarri on the west coast.
The year so far has been drier than average for the southeastern quarter of the mainland; for this region January to June 2018 has been the fourth-driest such period since comparable records commence in 1900.
15-month rainfall deficiencies
Above average June rainfall over the northwest of Western Australia has alleviated deficiencies in the coastal southeast of the Pilbara and northeastern Gascoyne, compared to the previous Drought Statement. Conversely, deficiencies have increased over large parts of eastern Australia and agricultural South Australia.
For the 15 months from April 2017 to June 2018, serious to severe rainfall deficiencies are in place across large areas of New South Wales (away from the southern border and northeastern coast); large areas of southern to central Queensland and small areas of western Queensland; across much of Gippsland in eastern Victoria; parts of South Australia about Lake Eyre / Kati Thanda, from Ceduna across the northern Eyre and York peninsulas, to parts of the Flinders Ranges and Murraylands District, and also Kangaroo Island. Deficiencies are also present along the western and southern coast of Western Australia from Shark Bay to around Esperance and scattered areas further inland, and along the east coast of Tasmania.
Soil moisture in the lower layer (from 10 cm to 100 cm deep) for June decreased over eastern Australia, and increased over parts of northwest Western Australia following above average rainfall for June.
Lower-layer soil moisture was below average for the Kimberley and southern Western Australia away from the west coast, most of South Australia and the Northern Territory, New South Wales and eastern Victoria, southern and eastern Queensland south of a line between Birdsville and Townsville, and along the coastal fringe of eastern Cape York Peninsula.
- June rainfall was below average for most of Australia, and very much below average for parts of the east coast
- The start of the southern wet season has been drier than average
- Rainfall deficiencies persist in both the east and west of the country, increasing in the east at the 6- and 15-month timescales, and along the west coast at the 15-month timescale
- Lower-layer soil moisture was below average for June across most of New South Wales, the southern half of Queensland, South Australia, the Northern Territory, the Kimberley and the south of Western Australia
Product code: IDCKGD0AR0
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.
For the week to 17 July, rainfall was recorded in western and the south coast of Western Australia; southeastern South Australia; western, northern central and far eastern Victoria; western and northern Tasmania; far northeastern New South Wales and the southeastern Queensland coast.
At the start of the week, a weak low pressure system and a cold front tracked over southeastern South Australia and western Victoria to produce moderate falls in these regions. The low then moved over eastern Victoria and generated showers and moderate falls in East Gippsland. Showers and moderate falls were recorded about the southeastern Queensland coast, due to an onshore southeasterly airflow.
In the middle of the week, a weak cold front tracked across southwest Western Australia. The system produced mainly light falls along the southwest coast., while the remainder of the country was mostly clear.
Towards the end of the week, a pair or cold fronts embedded in a vigorous westerly flow tracked over southern Western Australia, led by a thick cloudband. Showers were reported in the southern Gascoyne, the South West Land Division, and southern Goldfields areas with moderate falls in the southwest coast. As the cold fronts tracked eastwards, mostly light falls were recorded along the southeast coast of Western Australia and the exposed southern coast of South Australia. Heavier falls were recorded in western and northern Tasmania.
Rainfall totals in excess of 50 mm were recorded in isolated areas in southeast Queensland and the far southwest coast of Western Australia. The highest weekly total was 95 mm at Cape Moreton Lighthouse in Queensland.
Rainfall totals between 25 mm and 50 mm were recorded in western Tasmania, most of the Lower West and South West districts in Western Australia, a small area in southeastern South Australia, and a pocket of the southeast coast of Queensland.
Rainfall totals between 10 mm and 25 mm were recorded in the southern Gascoyne coast, much of the South West Land Division, and southern Goldfields in Western Australia; southeastern South Australia including Kangaroo Island; far southwestern, northern central and far eastern Victoria; western and much of northern Tasmania; and a small area of northeastern New South Wales and the southeastern Queensland coast.
Little or no rainfall was recorded in remaining parts of Western Australia, the Northern Territory, South Australia away from the southeast coast, central and northwestern Victoria, eastern Tasmania, most of New South Wales and most of Queensland.
Impact of recent rainfall on deficits
The Drought Statement, issued on 10 July 2018, discusses rainfall deficits over Australia for the 6-month (January–June 2018) and 15-month (April 2017–June 2018) periods. Rainfall deficit maps are available for these periods as well as for standard periods.
The maps below show the percentage of mean rainfall that has been received for the rainfall deficit period for the 6-month and 15-month periods ending 17 July 2018.
Rainfall for the period 1 January to 17 July 2018
Serious to severe rainfall deficiencies for the 6-month period are in place across much of New South Wales (except for the southeast and the northern coasts); adjacent areas of the Darling Downs and Far Southwest Queensland, and an area of the Central Highlands and Coalfields District; large areas of eastern South Australia, extending to the Eyre Peninsula; western to Northern Country Victoria, and smaller areas of Gippsland. Serious to severe rainfall deficiencies also persist in Western Australia in the South Coastal District and south of Shark Bay on the west coast.
Rainfall in the last week had little impact of deficiencies. Affected areas of central and northwestern New South Wales, southern Queensland and northeastern South Australia have mostly received between 20% and 40% of average rainfall for the period. Affected areas from southwest, and central to eastern New South Wales, northwestern Victoria, southeastern South Australian and southwest Western Australia received 30% to 60% of average for the period.
Rainfall for the period 1 April 2017 to 17 July 2018
Serious to severe rainfall deficiencies for the 15-month period are in place across much of New South Wales (except for the southeast and the northern coasts); adjacent areas of the Darling Downs and Far Southwest Queensland, and an area of the Central Highlands and Coalfields District; large areas of eastern South Australia, extending to the Eyre Peninsula; western to Northern Country Victoria, and smaller areas of Gippsland. Serious to severe rainfall deficiencies also persist in Western Australia in the South Coastal District and south of Shark Bay on the west coast.
Rainfall in the last week had little impact on deficiencies in affected areas. Affected areas about the northwest coast of Western Australia have generally received between 50% and 70% of average. Deficiencies in affected areas of Queensland, New South Wales and South Australia have received between 30% and 60% of average rainfall for the period.
Product code: IDCKGRWAR0