Special Climate Statement 77 - Persistent heavy rain and flooding in eastern Australia during spring 2022

21/09/2023

Issued: Thursday, 21 September 2023

The Bureau of Meteorology has released a formal record of the persistent heavy rain and flooding in eastern Australia during spring 2022.

Special Climate Statement 77 has details on the rainfall and catchment conditions around spring 2022. It also includes comparisons with previous rainfall records and flood events.

The statement found many sites across south-eastern Australia had their highest total spring rainfall on record, including more than 200 sites with at least 100 years of observations.

Persistent heavy rain during spring 2022 led to extensive riverine flooding in the Murray–Darling Basin in New South Wales and Victoria, and floodwaters moved into South Australia.

Significant flooding also affected parts of southern Victoria, southern Queensland and northern Tasmania. Some gauges exceeded their historical flood peaks during spring 2022, including:

• on the Lachlan and Murrumbidgee rivers in NSW,
• the Campaspe River at Rochester in Victoria and
• in the Tamar catchment in Tasmania.

Rain fell on catchments where water storages and river levels were high and soils were already wet after 2 years of above average rainfall.

Major weather systems brought significant rainfall to southern and eastern Australia with 4 months of very wet conditions between August and November 2022.

There were 3 major climate drivers influencing Australia's above average rainfall at this time: La Niña, a negative Indian Ocean Dipole and a positive Southern Annular Mode.

In comparing flood events, the Bureau looks at measures such as rivers reaching record new heights; and the number of areas affected by different flood levels and for how long.

While the 2010–11 flooding was more widespread nationally, flooding in the second half of 2022 was more prolonged in the southern Murray–Darling Basin. A greater number of river gauges in the southern Murray–Darling Basin stayed above flood levels for a record number of days in 2022.

The Bureau's special climate statements provide detailed information about significant weather and climate events that affect Australians. This Special Climate Statement has been added to an archive of Special Climate Statements dating back more than 16 years, providing easy access to data and information.

Special Climate Statement 77 can be found here on the Bureau's website: http://www.bom.gov.au/climate/current/statements