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.

A very dry month for the southeastern mainland increases rainfall deficiencies

April rainfall was below to very much below average for much mainland southeastern Australia, including Victoria, most of the southeastern quarter of South Australia, the eastern half of New South Wales and border regions of the west and south of that State. Below average rainfall extended into the inland southeast of Queensland, and affected eastern Tasmania, northern South Australia, most of the southern two thirds of the Northern Territory, and parts of western Queensland.

The persistence of strong high pressure systems over the southern Tasman Sea continued during April; this pattern has been a dominant feature for many months and again impeded the passage of cold fronts and intrusion of moist tropical air over the southeast of the continent. For the year to date (January–April), rainfall has been below to very much below average over much of Australia, and rainfall deficiencies have increased in extent and severity at each of the 4-, 7- and 13-month timescales across much of Victoria and southern South Australia.

In addition to a very dry start to the year for much of the country, it has also been the warmest January to April period on record for Australia.

The Climate Outlook for May indicates a lower than average chance of exceeding median rainfall across most of eastern Australia, and a strong probability of warmer than average temperatures. Over the longer period (May–July), the outlook is more neutral over eastern and southern Australia, meaning there is no strong tendency towards above or below average rainfall indicated during that time.

Despite above average April rainfall in parts of the west and north of the country, and in a band extending from Queensland's Central Coast, through parts of central and southern Queensland and into northwestern New South Wales, rainfall deficiencies persist.

The unusual length and severity of the current drought was discussed in a Special Climate Statement released last month.

Rainfall has been below average over very large areas for a prolonged period, extending beyond the 2-year timeframe that the Drought Statement traditionally encompasses. While the 25-month period has been removed from formal monitoring within the Drought Statement, Bureau climatologists will continue to track this long dry.

4-month rainfall deficiencies

The first four months of 2019 have brought a very dry start to the year, with April particularly dry for much of the mainland southeast, and a resulting increase in rainfall deficiencies.

Compared to last month, rainfall deficiencies have increased through most of Victoria, southern and western South Australia, much of the central to western Northern Territory south of the Top End, and along the eastern border of inland Western Australia.

Serious or severe rainfall deficiencies affect most of Victoria except the far northeast and far east of Gippsland; most of southern and central to western South Australia; most of the Northern Territory away from the Top End and the eastern border; the east of Western Australia's Interior District and the far southeast of that State, as well as pockets in the Southeast Coastal, Central West, and northern Kimberley districts; across northeastern New South Wales and southeastern Queensland; and along eastern and northeastern Tasmania.

Many farmers in southern Australia look to the autumn break—generally defined as the first significant rain event after summer—as the marker for the start of the crop and pasture growing season. In much of southern Australia that rain event has not yet come, although rainfall forecast for the first week of May might see some regions receive this much-anticipated rainfall.

7-month rainfall deficiencies

Northern Australia receives the bulk of its rainfall between October and April (the northern wet season), so rainfall deficiencies during this period are particularly significant, and will not usually be removed before the following wet season. With little rain over areas affected by rainfall deficits during April, it is now likely these rainfall deficiencies will persist until next spring.

However, rainfall during the month decreased deficiencies in the Gascyone in Western Australia, and in Queensland's Central Highlands.

A dry month for much of the southeastern mainland has resulted in an increase in 7-month rainfall deficiencies in this part of the country, compared to last month.

Serious or severe rainfall deficiencies for the seven-month period starting October 2018 are apparent in the northern Kimberley, the north of the Interior District, and pockets of the western Pilbara and to the north of Perth in Western Australia; a very large area in the central Northern Territory and pockets of the western Top End coast; along the border of New South Wales and Queensland, and a pocket of the southern Central Highlands in Queensland; parts of the eastern half of South Australia, including the Eyre, Fleurieu, and Yorke peninsulas; most of the southern half of Victoria; and in the west and south of Tasmania.

13-month rainfall deficiencies

Rainfall during April has reduced deficiencies in parts of Western Australia's Gascoyne, southwestern Queensland and northwestern New South Wales. Conversely, rainfall deficits have increased in Victoria and southeastern South Australia, and generally continue with little change elsewhere.

Serious or severe rainfall deficiencies are in place across central to eastern South Australia except parts of the far northeast and far southeast; across much of northern, central southern and eastern Victoria; across much of the Riverina in New South Wales as well as much of the west and northeast of that State; along the southern border of Queensland, extending across the greater southeast to around Taroom and Rockhampton; much of the Northern Territory away from the eastern border and much of the Top End; and across much of the Kimberley, northern half of the Interior District, and adjacent eastern Pilbara in Western Australia, as well as areas in the Central West, South Coast, and Southeast Coastal districts.


Soil moisture

Compared to March, there has been an increase in relative lower-layer soil moisture (from 10 cm to 100 cm deep) across parts of northern Australia, particularly about the coastal Pilbara, the southern and eastern Gulf of Carpentaria coast and Cape York, and across central Queensland to the east of the Northern Territory. Soil moisture has however decreased across the base of Cape York Peninsula, much of the Top End and the Kimberley, inland Western Australia, and the south of the Northern Territory and west of South Australia.

Soil moisture for April was below average for most of Victoria, South Australia away from the northeast, southeast Western Australia, much of the Northern Territory away from the Top End and the east of the Territory, the eastern half of the Kimberley, and the northeast of New South Wales.

Lower-layer soil moisture was raised to above average levels over much of Queensland following rain during April, soil moisture for the month also above average for pockets of New South Wales inland of the ranges and north of the Riverina, for northeastern South Australia, much of the eastern half of the Northern Territory, and areas along the coast of Western Australia between the western Kimberley and the northwestern Gascoyne, as well as along the inland edge of the South West Land Division and an area of the southern Interior District.

The low soil moisture during April extends the run of dry months this year, making the average soil moisture for January–April 2019 very much below average in many of these areas.

  • April rainfall below to very much below average for much of mainland southeastern Australia, but above average for Western Australia's Gascoyne, areas around the northern coast of Australia, and in a band between Central Coast Queensland and northwestern New South Wales
  • Above average rainfall in Queensland, but mostly over areas not experiencing serious or severe rainfall deficiencies, thus having little effect on rainfall deficits
  • Rainfall deficiencies have increased across much of Victoria and southern South Australia
  • Lower-level soil moisture below average for April across most of Victoria, South Australia, and the west of the Northern Territory; above average for much of Queensland, extending into adjacent areas
  • Equal-seventh-warmest April on record for Australia continues a run of warm months, adding to moisture stress

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