Isolated areas of rainfall deficiencies persist in some areas following a wet winter
Rainfall during August 2016 was above to very much above average for most of the country, especially northern and central Australia and parts of New South Wales. Rainfall for the month was below average for eastern Tasmania, southeastern New South Wales, across Gippsland and pockets of the Western district in Victoria, areas of southern South Australia—particularly around the Eyre Peninsula—and parts of Western Australia's Interior district, although rainfall totals are generally low there during August.
Generally above average rainfall in August follows above average rainfall over most of the country in each month since May 2016, providing excellent relief from the multiyear rainfall deficiencies which had developed in the 2012 to 2015 period. However, some small areas continue to experience rainfall deficiencies in southern Victoria and around the northern and western coast. Overall, winter 2016 was the second-wettest for Australia. Most areas now have average to above average soil moisture, and the area of severe and serious rainfall deficiencies is greatly reduced. Higher than average rainfall often occurs following the breakdown of strong El Niño events, and has further been enhanced by the strong negative phase of the Indian Ocean Dipole (IOD) which has persisted since late May.
Soil moisture in the lower layer (from 10 cm to 100 cm deep) remains above average over most of the country.
Soil moisture for August was above average over much of Australia, and very much above average for central Queensland to the western Cape York Peninsula, much of New South Wales west of the Great Dividing Range, a large part of central to eastern Tasmania, and for the Pilbara in Western Australia and western areas of Central Australia.
Soil moisture for the month was below average for part of the South West Land Division in Western Australia and parts of the central Top End.
- Rainfall deficiencies persist in isolated pockets of the northern and western coast and southern Victoria
- Lower layer soil moisture for August was above average over most of 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 20 September 2016, rainfall was recorded in southwest Western Australia, and the Northern Territory, southern, central and eastern South Australia, Victoria, Tasmania, New South Wales, and much of Queensland.
Early in the week, a middle-level trough and an associated cloudband moved across central Australia, producing moderate to heavy rainfall across southern Queensland, and northeast New South Wales. Meanwhile, a low pressure system over western Victoria tracked southeast through Bass Strait and Tasmania, producing widespread rainfall across much of eastern Australia including heavy rainfall on the Mount Lofty ranges in South Australia. In the west a weak cold front tracked across southwest Western Australia bringing light to moderate rainfall along coastal areas.
During the second half of the week an upper-level trough and associated surface trough extended across the Northern Territory, western Queensland and southeastern Australia. Significant daily rainfall totals were recorded, with areas affected including the western, central and southern interior districts of Queensland. Moderate falls were also reported across the northeast Pastoral district of South Australia and western parts of New South Wales. Another cold front moved across the southwest Western Australia bringing light to moderate rainfall to the region.
At the end of the week a deep trough of low pressure located over the Top End of the Northern Territory brought unseasonably heavy rainfall for many locations in Arnhem Land. Moderate to heavy rainfall was also recorded across southern parts of the Northern Territory and central areas of South Australia ahead of the approaching cold front.
Rainfall totals in excess of 100 mm were recorded around the Van Diemen Gulf and eastern Top End, pockets of the southern Northern Territory, isolated areas of northeast New South Wales, scattered areas of southern to western Queensland and across the Mount Lofty ranges in South Australia. The highest weekly total was 230 mm at Bulman in the Carpentaria district of the Northern Territory.
Rainfall totals between 50 and 100 mm were recorded in the Top End, also across a broad area extending across the southern half of the Northern Territory, through western and central Queensland to inland northeast New South Wales. Similar totals were recorded on Kangaroo Island in South Australia, central and northeastern Victoria and large areas of the western and eastern Tasmania.
Rainfall totals between 10 mm and 50 mm were recorded in southwest Western Australia, in southern and eastern South Australia, in Victoria and Tasmania, most of New South Wales away from the northwest, much of Queensland apart from the tropical north and east coast, much of the Northern Territory.
Little or no rainfall was recorded in remaining parts of Western Australia, much of the tropical north of Queensland and the northwest of South Australia.
Impact of recent rainfall on deficits
Due to above average rainfall in recent months over areas which had experienced deficiencies since mid-2015, no large-scale deficiencies are currently present. Rainfall analyses are available for standard periods out to 48 months.
Product code: IDCKGRWAR0