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.
Rainfall deficiencies continue and increase in severity for the east
Nationally, it was the driest July since 2002 and below average for most of southern Australia. The Goldfields and Southern Interior districts of Western Australia, areas in the south and northeast of South Australia, into New South Wales and northern Victoria all very much below average. Rainfall was the lowest on record for July in parts of northern inland and west slopes of New South Wales, across the border into the eastern Pastoral region of South Australia and patches in the Goldfields of Western Australia.
Despite the month overall being very dry, there were areas that received above average rainfall in southwest Western Australia, the northeast coast of the Top End, far north coast of Queensland and most of Tasmania.
Rainfall deficiencies have increased in both areal extent and severity for almost all of New South Wales, inland southern Queensland, northern Victoria (less so in southeast either side of the Victoria and New South Wales border), eastern Pastoral and southern Agricultural regions of South Australia, and southern and Gascoyne coast of Western Australia at both the 7- and 16-month timescales.
A dry first half of the southern wet season
The southern wet season spans April to November and corresponds to the southern agricultural cropping season. The exceptionally dry conditions experienced over the first half of the season has seen a large area along the Western Australia's southern coast (near Esperance) and a smaller patch in the northwest slopes and plains of New South Wales receiving record-low rainfall for the 4 month period.
As a consequence of the past several months of exceptionally low rainfall, 39% of Australia's landmass is in the lowest 10% of historical observations for rainfall for the April to July period. For this period, 83% of New South Wales falls below the 10th percentile. Both Western Australia and South Australia began drying slightly earlier in the year.
7-month rainfall deficiencies
The dry July has exacerbated rainfall deficiencies already being seen over much of the southeast of the mainland. Compared to the previous Drought Statement, deficiencies have increased in severity and spread through most of New South Wales and northern Victoria (apart from the far southeast corner near the border), southern Queensland, the eastern half of South Australia in the Agricultural and east Pastoral regions and in the southwest coast of Western Australia.
Year to date rainfall deciles show significant dryness in the southeast of the mainland and the southwest corner of Western Australia. Consequently, deficiencies have continued, intensified and expanded over most of New South Wales, southwestern Queensland, and the northeastern Agricultural and Pastoral districts of South Australia. The Western Australia's South Coastal District has expanded with a slightly larger area now in severe deficiency.
Areas of lowest on record rainfall have enlarged in far northwest New South Wales and in the Murraylands region of South Australia and across the border into northwest Victoria.
16-month rainfall deficiencies
Deficiencies have persisted at longer timescales. For the 16 months starting in April 2017, the extent and severity of rainfall deficiency has continued over areas of New South Wales (away from the southern border and northeast coast), large areas of southern to central Queensland and smaller areas of western Queensland, across much of Gippsland in eastern Victoria and the Eyre peninsulas and west to the Murraylands District in South Australia. Deficiencies also continue along the western and southern coast of Western Australia from Shark Bay to around Esperance and have expanded further inland into southeast Wheatbelt region.
Serious to severe rainfall deficiencies are evident across most of the northern two-thirds of New South Wales except the north coast, much of the southeast corner of South Australia, southern Agricultural and Pastoral regions and along the Eyre Peninsula, Warrego and central west Queensland, and coastal areas of the Southwest Land Division in Western Australia.
Some areas of northern inland and the southeast coast of New South Wales have registered lowest on record rain for the 16 months from April 2017 to July 2018.
Some rain in southern Queensland in July and central north New South Wales during June has increased lower-layer soil moisture (from 10 cm to 100 cm deep) for July in these regions, but soils remain relatively dry over much of the eastern three quarters of the mainland, and very dry in several areas.
Soils have moistened in the southwest corner and northwest of Western Australia and a large area in the Southern Interior, with some areas showing above average soil moisture. Below and very much below average lower-layer moisture is evident for the Kimberley and southern Western Australia, into the Goldfields region and away from the west coast; most of the Northern Territory and South Australia, much of New South Wales specifically west of the Great Dividing Range; the eastern half of Victoria; and southern, central interior and coastal Queensland.
- Low rainfall and warm temperatures during July
- Rainfall deficiencies have increased at 4- and 7-month timescales both in areal extent and severity for most of New South Wales, Agricultural and east Pastoral regions of South Australia, northern Victoria and southern coastal Western Australia
- The first half of the southern wet season exhibits serious to severe rainfall deficiencies across much of the southern half of the country
- Lower-level soil moisture was drier than average for July
Product code: IDCKGD0AR0