Rainfall deficiencies and water availability
Climate of the 2018–19 financial year
Drier than average over much of Australia, leading to an intensification of drought conditions especially in the northern half of the Murray-Darling Basin. Second-warmest financial year on record created additional water stress for many areas. Read more...
Rainfall deficiencies continue following driest November on record
It was Australia's driest November and spring on record. November rainfall was below to very much below average across most of Australia, including much of northern and eastern Queensland, eastern New South Wales, South Australia, Western Australia, and the Northern Territory.
For the year to date (January–November), rainfall has been below to very much below average over much of Australia. For Australia as a whole, it was the second-driest January–November on record, behind January–November 1902. Daytime temperatures have also been very warm, second highest on record for mean maximum temperature, adding to moisture stress. A recent climate update on the year-to-date and likely end-of-year scenarios is available.
Widespread rain and scattered thunderstorms associated with a slow-moving trough and cold front in the first days of November brought rainfall across some areas of eastern Australia. Through some areas of inland Queensland and central to western New South Wales this event has brought the first significant rainfall since early May. During this event Bourke had its wettest November day on record. This rain cleared short-term (4 month) deficiencies in the area around Bourke, but long-term deficiencies remain.
Rainfall anomalies at longer timescales are very deep due to the prolonged nature of the current dry period, with below average rainfall over most months over much of the country since early 2017. Consistent, widespread, above average rainfall over several months will be needed to lift areas out of deficiency and provide relief from the impacts of this long period of low rainfall (such as renewing water storages).
Whilst the Bureau of Meteorology's monthly Drought Statement focuses on rainfall deficiencies for periods up to two years' duration, we monitor rainfall deficiencies and impacts on water resources on longer timescales such as the current severe multi-year drought affecting large parts of eastern Australia. This is discussed further below, and we have Special Climate Statements on this long-term period.
The role of climate change in rainfall reduction over southern Australia is discussed in State of the Climate 2018. Parts of southwest Australia, and large parts of southeast and eastern Australia including parts of southeast Queensland and southern and eastern New South Wales have seen substantial declines in cool season rainfall in recent decades.
The Climate Outlook for December to March, issued 28 November, indicates a drier than average end of the year is likely for most of Australia. The chance of exceeding median rainfall for December is less than 35% over much of eastern Australia. The lower odds of receiving average or above average rainfall is likely being influenced by the positive Indian Ocean Dipole. The IOD typically wanes with the start of the northern monsoon, however, given the current positive IOD is so strong, it is likely to take several weeks to decline, and could persist well into mid-summer. It should also be noted that southern states are moving into their drier time of the year, which typically brings a seasonal drop in water storages over summer months.
4-month rainfall deficiencies
A record-dry November for Australia has continued rainfall deficiencies at shorter timescales.
Rainfall for the 4 months from August to November 2019 has been record low over much of northeastern New South Wales. Areas of short-term rainfall deficiency in the central north of the State have been cleared following above average rainfall in this region in November. Serious to severe rainfall deficiencies extend across eastern and southern New South Wales inland of the ranges; across northern Victoria and East Gippsland; across much of southern Queensland and large parts of the north of that State; northern Tasmania; South Australia; southern parts of Western Australia ; and large parts of the Northern Territory.
11-month rainfall deficiencies
Areas of rainfall deficiencies for the year to date remain very similar to those present at the end of October with some increase in severity and extent in the Northern Territory and northern parts of Western Australia. Around 60% of Australia is in decile 1 (lowest 10% on record) for the period.
In New South Wales, serious to severe rainfall deficiencies extend across most of the North West Slopes and Northern Tablelands, along with coastal areas from the Hunter northwards. Areas of serious to locally severe deficiencies also exist across the southern coast of New South Wales, and between the New South Wales Tablelands and the Central District in Victoria, as well as in inland to coastal central Gippsland. In Queensland, serious to severe rainfall deficiencies affect the greater southeast, the eastern Maranoa, and the Capricornia District. Areas of record low rainfall cover an area extending from the Southern Downs in Queensland to the New South Wales' central Northern Tablelands, Northwest Plains, and part of the Mid-North Coast district. In some areas, particularly in the Northern Tablelands and North West Slopes and Plains in New South Wales and the Southern Downs in Queensland, rainfall for January–November 2019 is more than 30% below previous record lows.
Serious to severe rainfall deficiencies are also evident across much of central and southern parts of the Northern Territory away from the Queensland border; most of South Australia except parts of the southeast, western Eyre Peninsula, and far northeast; across western New South Wales; the Mallee and parts of eastern Victoria; and coastal parts of northeastern Tasmania. In Western Australia serious to severe rainfall deficiencies affect most of the interior of that State, nearly all areas along the south coast and most of the Southwest Land Division, and parts of the Pilbara and Kimberley. A large area has observed lowest on record rainfall for January–November, particularly in the central Northern Territory, and around the Alice Springs District, pastoral South Australia, and central eastern Western Australia.
20-month rainfall deficiencies
Rainfall deficiencies for the period April 2018 to November 2019 remain generally similar to those for the period April 2018 to October 2019 but have increased somewhat in severity in the Northern Territory.
Serious to severe rainfall deficiencies are in place for the 20-month period from April 2018 to November 2019 across much of the northern half of Western Australia, except parts of the inland Kimberley, the central and southwestern Pilbara, and northeastern Gascoyne; across much of the South West Land Division in Western Australia; much of the Northern Territory except much of the Top End and eastern border; much of South Australia; southern and southeastern Queensland, extending across much of the Central Highlands and Capricornia districts; most of New South Wales; across northern Victoria and most of the eastern half of that State except parts of West and South Gippsland; and near Tasmania's east and north coasts.
Much of the northeast inland of New South Wales has had record low rainfall for the 20-month period, as have parts of adjacent southern Queensland, areas of western New South Wales to eastern South Australia, large parts of central areas of the Northern Territory into Western Australia and scattered pockets elsewhere.
Extended dry conditions over eastern Australia
Rainfall deficiencies have affected most of New South Wales, Queensland and South Australian parts of the Murray–Darling Basin since early 2017, as detailed in a recent update on the long-running dry. These longer-term deficiencies extend to parts of the New South Wales coast, particularly in the Hunter and Illawarra to southeastern districts, and to much of the eastern half of South Australia from Adelaide northwards. The deficiencies have been most extreme in the northern Murray–Darling Basin, especially in the northern half of New South Wales and adjacent southern Queensland, where areas of lowest on record rainfall extend across large parts of northeastern New South Wales inland of the Great Dividing Range to as far west as Dubbo and Walgett, as well as smaller areas on central and northwestern New South Wales and southern Queensland. Some of the largest rainfall deficiencies have occurred in the upper catchments of some of the major tributaries of the Darling, including the Macquarie, the Namoi–Peel, and the Border Rivers.
When compared to other 35-month periods commencing in January, the 35 months from January 2017 to November 2019 has been the driest on record averaged over the Murray–Darling Basin (36% below the 1961–1990 average), and for the state of New South Wales (also 36% below average). New South Wales received over 100 mm less rainfall than the next driest period, ending November 1902 during the Federation Drought. Other areas affected by longer-term rainfall deficiencies include eastern Victoria, eastern and northern Tasmania and some parts of southwest Western Australia.
The dry conditions of the last three years have been particularly acute during the cool season, which is important in many regions for generating runoff. April−September rainfall totalled across the three years was the lowest on record across almost all New South Wales, apart from some coastal areas and parts of the far west, as well as in most of subtropical Queensland. All three years had seasonal rainfall below 125 mm for New South Wales; there is no previous instance of two consecutive years below 125 mm, or three consecutive years below 175 mm. The very much below average October and November rainfall in 2019 over most of the main water catchments of New South Wales and the Murray–Darling Basin as a whole has further exacerbated the effect of low inflows to date.
Limited inflows to major water storages in the Murray–Darling Basin
The dry soils absorbed most of the rain that fell across the Murray–Darling Basin during November, resulting in limited runoff and very low inflows to the major storages.
The storages in the northern Murray–Darling Basin remain extremely low, having received no significant inflows. Collectively, the major storages of the northern Basin are now at 6.3% of capacity, a decline of 0.3% from last month. Some of the lowest major storages are Keepit and Split Rock in the Namoi valley at 0.8% and 1.1% respectively, Burrendong in the Macquarie valley at 3.1% and Copeton in the Gwydir valley at 6.9%. Further down the Darling river system, three of the four Menindee Lakes are empty. Many towns in the region, including Dubbo, have raised their water restriction levels again this month and are investigating alternative water sources, such as groundwater, to augment their water supply.
The volume of water in storage in the southern Murray–Darling Basin also dropped again in November. This follows the start of irrigation seasons in August and reduced inflows to the major storages due to dry catchments and limited rain. The Hume dam, the third largest storage in the Basin, has dropped over 5% to 33% of capacity this month. It is expected that the total storage volume in the southern Murray–Darling Basin will continue to decrease until late April as this is on average the period when the bulk of downriver releases occur, and inflows are lower.
Continued low streamflows in the northern Murray–Darling Basin
Streamflows have been average to lowest on record during November right across the Murray–Darling Basin. Very few of the northern Basin rivers are flowing at all and while this is not unusual for some of the northwestern rivers, the rivers in the northeast are seeing lowest on record flows for this time of year. There are minor flows still running through some of the rivers downstream of the storages in the Namoi, Macquarie, Gwydir and Border Rivers, largely due to minor releases from the storages but this water is not making it to the lower sections of these rivers or into the Darling River.
The rain that fell in northwest NSW in early Novermber did deliver some local flows to the Warrego and Darling rivers near Bourke. These flows made it downstream as far as Tilpa but most sections of the rivers have now ceased to flow (see Water Data Online).
The streamflow in the southern Murray–Darling Basin ranges from average to very much below average, with the exception of the lower Darling River. The Darling river at Menindee recorded lowest on record with no flow at all in November.
Streamflow is influenced by both water released from major storages and consumptive take from the rivers, in addition to natural runoff from rainfall. There have been some increases in soil moisture in the northern Basin but it is clear that very little of the rain is running off the landscape and into the rivers and storages. Until significant rain occurs the rivers and storages will continue to decline through water use.
Urban water storages
The amount of water in all the major urban storage systems decreased in November except for Melbourne and Hobart which saw minor increases. The decreases were all approximately 2% with Brisbane dropping below 60% for the first time since 2009.
Sydney's major water storage levels continue to fall prompting another increase in water restrictions
Lower than average rainfall combined with very dry soils has resulted in very low runoff from large areas of the Sydney water storage catchments. The great Sydney area received lower than average rainfall with very much below average seen in the southern catchments. As a result, Sydney water storage levels continued to fall despite the desalination plant operating at full capacity and the implementation of Level 1 water restrictions in June. Accessible storage levels fell to 45.8% of capacity, a decline of 1.7%, during November prompting an announcement from Sydney Water of a planned increase in water restriction to Level 2 on the 10th of December.
Sydney storage catchments are exceptionally dry with average soil moisture at the 2nd lowest on record for November and 5th lowest on record for any month since 1911. The storage levels in Warragamba Dam, Sydney's largest water storage, have been declining since July 2016. Some rain has fallen during this time, but the soil has soaked up a significant proportion of the water and releases have continued to be made to supply Sydney. With the current exceptionally low soil moisture in the catchments, significant rain will be required to generate increases in soil moisture to the point of producing runoff and inflows to these storages.
November soil moisture in the root zone (from 0 to 100 cm deep) deciles were similar to those for October over much of Australia. Rainfall at the start of the month in western New South Wales has eased deficiencies there. Soil moisture for November was below average for eastern New South Wales; eastern Queensland; northeast Victoria; northeast Tasmania; much of South Australia; most of western and southern Western Australia, and pockets of the Kimberley; and much of theNorthern Territory.
The relatively dry soils seen during November extends the run of dry months this year. Soil moisture for January–November 2019 was very much below average over very large areas of Australia.
Soil moisture increase through the central Murray–Darling Basin
The rain in early November slightly eased the dry soil moisture conditions in large parts of the Murray–Darling Basin. None of the Murray–Darling Basin catchments registered lowest on record soil moisture this month, compared to six catchments in October.
The rain was centred around Bourke but conditions eased slightly throughout the central and western Basin. The soils are still extremely dry along the east coast of NSW but the proportion of the state experiencing very much below average soil moisture in November reduced to 25% compared to 72% in October.
Soils remain very dry in the northeast of the Basin and down along the western side of the Great Dividing Range where the majority of the inflows to the Darling River system originate.
The catchments in the southern Basin that received near average rainfall during late autumn to early winter continue to dry out. In the upper reaches of the major water yielding catchments of the Goulbourn and Ovens rivers the available soil water content has dropped by up to another 10% and remains below average.
Despite some increases in soil moisture during November, long-term records in low soil moisture continue to be set. The catchment average soil moisture over the past 35 months (January 2017 to November 2019) remains the lowest on record in ten of the 26 river catchments in the Murray–Darling Basin.
- November rainfall lowest on record for Australia
- Rainfall deficiencies continue in many areas, with some increases across northern Australia
- Long-term rainfall deficiencies, record-low for some periods, continue to severely limit water resources across the Murray–Darling Basin
- Inflows remain limited to major water storages in the Murray–Darling Basin
- Slight increases in soil moisture in the central Murray–Darling Basin
- Sydney water storage levels continue to fall prompting increase in water restrictions
Product code: IDCKGD0AR0
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?
Go to Bureau Blog: 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:
- Know your weather
Know your weather. Know your risk.
- 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.
For the week to 10 December 2019, rainfall was recorded in the Kimberley and southwest of Western Australia; in the northwestern parts of the Northern Territory; in northern and southeastern Queensland, and the western half of Tasmania. Light rainfall was recorded in the far southeast of South Australia and southern Victoria.
At the start of the week, a surface trough extending from the country's northwest and the Top End, and into northwestern Queensland triggered thunderstorms in the Kimberley in Western Australia, northwestern parts of the Northern Territory, and the Cape York Peninsula in Queensland. A westerly flow produced light rainfall in southern Victoria and moderate falls in western Tasmania.
In the middle of the week, a high pressure system became established in the Bight and dry air dominated most of the country. Rainfall was restricted to the north tropical and southeast Queensland coasts from an onshore flow, whilst the westerly flow continued to produce moderate rainfall in western Tasmania. A weak cold front brought mostly light rainfall over southwest Western Australia.
At the end of the week, most of southern Australia was dry with a high pressure system in the Tasman Sea and another high in the Bight. A surface trough across the tropics produced isolated thunderstorms in the Kimberley, northwestern Northern Territory, and Gulf Country in Queensland. The northern tropical coast in Queensland recorded moderate falls from onshore flow, while isolated thunderstorms brought moderate falls to parts of the Wide Bay and Burnett District in southeast Queensland.
Rainfall totals in excess of 50 mm were recorded in western Tasmania, including the highest weekly total of 233 mm at Mount Read. Rainfall totals between 50 mm and 70 mm were also recorded in isolated spots in the western Kimberley in Western Australia, the Darwin-Daly region in the Northern Territory, and the Cape York Peninsula in Queensland.
Rainfall totals between 10 mm and 50 mm were recorded in the west Kimberley region of Western Australia, in northwestern parts of the Northern Territory, and areas of northern and southeast Queensland. Rainfall totals between 10 mm and 15 mm were recorded in small areas in the southwestern tip in Western Australia; also in southern Victoria.
Little or no rainfall was recorded in most of Western Australia, the Northern Territory, Queensland away from the northern and east coast parts, South Australia away from the southeast, most of Victoria, New South Wales, and the northeastern half of Tasmania.
Impact of recent rainfall on deficits
Rainfall deficits over Australia for the 4-month (August-November 2019), 11-month (January–November 2019) and 20-month (April 2018–November 2019) periods are discussed in the Drought Statement, issued last week.
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 4-month, 11-month and 20-month periods, extended to the week ending 10 December 2019.
Rainfall for the period 1 August to 10 December 2019
Serious to severe rainfall deficiencies extend across New South Wales inland of the ranges; across northern Victoria and East Gippsland; across much of southern Queensland and parts of the central north of that State; northern Tasmania; large areas of western, northern, and eastern South Australia away from the northeast and the southeast; large areas of Western Australia between the southern Pilbara and Gascoyne, extending into the western Interior, as well as parts of the south and along the South Australian border; and for inland parts of the western Top End in the Northern Territory.
Rainfall during the past week had very little effect on rainfall deficiencies in most affected areas. Areas in parts of southern inland Queensland and inland northeastern New South Wales have received less than 30% of the average rainfall.
Affected areas of New South Wales and adjacent southern Queensland, northern Queensland, and South Australia have mostly received less than 40% of average rainfall for the period, except for an area around the Upper Darling which has received between 50% and 100% of average rainfall.
Affected areas of Victoria, Tasmania, and Western Australia have mostly received between 40% and 70% of average rainfall for the period, dropping to less than 40% in the northern South West Land Division and Gascoyne in Western Australia.
Rainfall for the period 1 January to 10 December 2019
In New South Wales, serious to severe rainfall deficiencies extend across most of the North West Slopes and Northern Tablelands, along with coastal areas from the Hunter northwards. Areas of deficiencies also exist across the southern coast of New South Wales, and between the New South Wales Tablelands and Central District in Victoria, as well as in inland to coastal central Gippsland. In Queensland, serious to severe rainfall deficiencies affect the greater southeast, the eastern Maranoa, and the Capricornia District.
Serious to severe rainfall deficiencies are also evident across much of the central and southern Northern Territory away from the Queensland border; most of South Australia except parts of the southeast, western Eyre Peninsula, and far northeast; across western New South Wales and the Mallee in Victoria. In Western Australia serious to severe rainfall deficiencies affect most of the interior of that State, nearly all areas along the south coast and most of the Southwest Land Division, and parts of the Pilbara and Kimberley.
Deficiencies persist in eastern Tasmania, and have expanded along the northeast coast.
Rainfall during the past week has had very little effect on rainfall deficiencies for the period starting January 2019.
Affected areas of northeastern and western New South Wales and southeastern Queensland have generally received less than 50% of average rainfall for the period, dropping to less than 30% of average for some areas along the border and in the Northwest Slopes and Plains District in New South Wales.
Affected areas of the South West Land Division and Kimberley in Western Australia have mostly received between 50% and 80% of average rainfall, while affected areas in agricultural South Australia, and the scattered areas affected in southeastern New South Wales, Victoria, and Tasmania have mostly received at least 60% of average rainfall.
Through Australia's interior, areas affected by serious of severe rainfall deficiencies in pastoral South Australia, the Northern Territory, and Western Australia's Interior, southeast, and northwest have largely received less than 40% of average.
Rainfall for the period 1 April 2018 to 10 December 2019
Serious to severe rainfall deficiencies are in place for this longer timescale across much of the northern half of Western Australia, except parts of the inland Kimberley, the central and southwestern Pilbara, and northeastern Gascoyne; across much of the South West Land Division in Western Australia; much of the Northern Territory except much of the Top End and eastern border; most of South Australia, except parts of the north, southwest, western Eyre Peninsula, and the southeastern tip; southern and southeastern Queensland, extending across much of the Central Highlands and Capricornia districts; most of New South Wales, except some pockets of the central coast, far southeast, and inland west; across northern Victoria and most of the eastern half of the State except parts of West and South Gippsland; and in Tasmania's east and north coast.
Rainfall during the past week has had very little effect on rainfall deficiencies for the period starting April 2018.
Affected areas through the interior of Australia have generally received less than 50% of average rainfall for this period. Affected areas of southern and eastern New South Wales and southeastern Queensland have generally received less than 60% of average rainfall, dropping to 30 to 40% in part of the inland slopes and plains region along the New South Wales—Queensland border.
Affected areas of southeastern New South Wales, Victoria, southern South Australia, Tasmania, and the South West Land Division in Western Australia have mostly received between 60% and 80% of average.
Affected areas of the Kimberley in Western Australia have mostly received between 40% and 60% of average rainfall for the period.
Product code: IDCKGRWAR0