Australia in April 2022

In brief

• April rainfall was 27% above average for Australia as a whole
• Rainfall for April was above average for most of the eastern half of Australia, much of western and south coast Western Australia, and an area of the western Top End and adjacent northern Kimberley
• Significant flooding affected parts of eastern Australia during the month
• Rainfall was below average for western Tasmania, coastal south-eastern South Australia, south-western Victoria, and a large area of Central Australia spanning the south-west of the Northern Territory and interior of Western Australia
• It was Australia's 7th-warmest April on record (mean temperature, compared to all years since 1910); while national mean maximum temperature was the 9th-warmest on record and national mean minimum temperature was the 3rd-warmest on record
• Mean maximum temperatures for April were warmer or very much warmer than average for much of northern and central Australia, South Australia and Tasmania, and parts Victoria; mean maximum temperatures were highest on record for April for some parts of the Northern Territory across the base of the Top End, and for parts of the inland northern Kimberley
• Mean maximum temperatures for April were cooler than average for much of the South West Land Division and part of the Gascoyne and western Pilbara in Western Australia
• Mean minimum temperatures for April were warmer or very much warmer than average for most of Australia, although they were close to average for parts of the west of Western Australia and the Kimberley

Temperatures

The national mean temperature for April was 1.61 °C warmer than the 1961–1990 average for Australia as a whole, and the 7th-highest on record for April. Only New South Wales, Victoria, and Western Australia observed mean temperatures for the month which were outside the ten warmest on record for April.

The national mean maximum temperature for April was 1.51 °C warmer than average, the 9th-warmest on record for Australia as a whole. Tasmania observed its 7th-warmest mean maximum temperature on record for April, and the Northern Territory its 5th-warmest.

The national mean minimum temperature for April was 1.71 °C warmer than average, the 3rd-warmest on record for Australia as a whole. Western Australia was the only region to observe a mean minimum temperature which was outside the ten warmest on record for April.

Mean maximum temperatures for April were warmer or very much warmer than average for much of northern and central Australia and in south-eastern South Australia, most of western and southern Victoria, and all of Tasmania. April days were very much warmer than average (decile 10, the highest 10% of historical observations) across much of the northern tropics, and warmest on record for April for some parts of the Northern Territory across the base of the Top End, and for parts of the inland northern Kimberley. Several stations in this region had their highest mean maximum temperature on record for April, as did a few stations around Cape York Peninsula in Queensland.

Mean maximum temperatures for April were cooler than average for much of the South West Land Division and part of the Gascoyne and western Pilbara in Western Australia.

Mean minimum temperatures for April were warmer or very much warmer than average for most of Australia, although they were close to average for parts of the west of Western Australia and the Kimberley. A large number of stations in south-east South Australia, Victoria, southern New South Wales, and along the coast of New South Wales into far south-east Queensland had their highest mean monthly minimum temperature on record for April.

Warm days early in the month resulted in records being set for highest daily maximum or minimum temperature at some stations in northern Queensland and across the north and west of the Northern Territory around the 2nd and again on the 11th and 12th.

Many sites in coastal south-west Western Australia many sites had their warmest minimum temperature on record for April during the 24 hours to 9am on the 2nd.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries, to be released on Wednesday 4 May 2022.

Rank ranges from 1 (lowest) to 113 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Anomaly is the departure from the long-term (1961–1990) average.

Rainfall

April rainfall was 27% above average for Australia as a whole.

Rainfall for April was above average for most of New South Wales and Queensland, although rainfall for the month was generally close to average for parts of north-eastern New South Wales, extending to the Hunter District, and parts of greater south-eastern Queensland and the Wide Bay and Burnett region. Rainfall for the month was also above average for parts of the eastern border of the Northern Territory, much of western and south coast Western Australia, an area of the western Top End and adjacent northern Kimberley, and much of South Australia away from the south-east and west of the state.

For Queensland and New South Wales area-average April rainfall was the 9th-highest on record (compared to all years since 1900). Some stations observed their highest total rainfall on record for April in areas of the central and southern coast of New South Wales, some through the centre of the state, and some in Queensland in parts of south-east and the northern tropical coast and central coast. However, monthly total records were nearly all set at stations with 20 or fewer years of observations.

Rainfall was below average for western Tasmania, coastal south-eastern South Australia, south-western Victoria, a large area of Central Australia spanning the south-west of the Northern Territory and interior of Western Australia, and also for some scattered areas of greater south-eastern Queensland.

A few stations along the west coast of Western Australia received record-high daily rainfall totals in the first few days of April, as did a few other station on the south coast of Western Australia on the 12th and 13th.

In the rest of the country, a few stations on the ranges near the border of New South Wales and Queensland had record-high daily rainfall for April in the 24 hours to 9am on the 4th; a few set records on the 7th or 8th in central coast New South Wales; and a scattering of daily records were set late in the month in South Australia inland of the Eyre Peninsula, north coast and east coast Tasmania, and across northern Queensland.

Significant flooding affected parts of eastern Australia during the month

At the beginning of the month, a deep low-pressure system off the southern coast of New South Wales and a high-pressure system centred south of South Australia funnelled moist south-to-south-easterly flow over south-eastern New South Wales, eastern Victoria, and north-eastern Tasmania. Significant rain fell over Gippsland, with flood warnings issued for several catchments.

By the 6th, a moist easterly airflow was being directed onto the coast of New South Wales by the high pressure system, now in Bass Strait, and a trough extending through from western Queensland into the northern interior of New South Wales. Rain falling onto already wet catchments saw a renewed period of flooding, with evacuation orders affecting more than 2,000 residents across Greater Sydney on the 7th.

A low pressure trough moving northwards along the Tropical North Queensland coast brought heavy rain to coastal areas of tropical Queensland in late April, mostly between the 21st and 26th. The highest multi-day totals were observed around the Daintree region, although rainfall was widespread, with some areas of western Queensland receiving well in excess of their average monthly rainfall for April.

Larger-scale climate drivers contributing significant rainfall during March and April 2022 have included La Niña in the tropical Pacific Ocean, very warm sea surface temperatures over the Tasman Sea and around north-west Australia, persistent high pressure in the Great Australian Bight related to a positive phase of the SAM (Southern Annular Mode), already wet soils, and climate change. As the climate warms, heavy rainfall events are expected to continue to become more intense — see State of the Climate 2020. A warmer atmosphere can hold more water vapour than a cooler atmosphere; this relationship can increase moisture in the atmosphere by 7% for each degree of global warming, which in turn increases the likelihood of heavy rainfall events. Increased atmospheric moisture can also provide more energy for some processes that generate extreme rainfall events, which further increases the likelihood of heavy rainfall due to global warming.

Conversely, while La Niña typically leads to above average summer rainfall for much of eastern Australia, there is no strong signal south of the Dividing Range in Victoria. Below average rainfall in western Victoria, western Tasmania, and parts of south-east South Australia in recent months has been influenced by persistent anti-cyclones ("blocking highs") in the Australian Bight and southern Tasman Sea, which have diverted cold fronts and moist tropical air away from the region. A persistent positive phase of the Southern Annular Mode (SAM), and La Niña in the tropical Pacific have also contributed to this. The Bureau's State of the Climate 2020 reported that April to October rainfall for south-eastern Australia has declined around 12% since 2000, compared to 1900–1999 rainfall. This is due to a shift in weather patterns as a known response to global climate change.

Further discussion and tables of records for each state and the Northern Territory can be found in the individual regional climate summaries, to be released on Wednesday 4 May 2022.

Rank ranges from 1 (lowest) to 123 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Departure from mean is relative to the long-term (1961–1990) average.