The year saw a transition from a very dry three-year period to a year of average to above average rainfall, influenced by a La Niña event, which was declared by the Bureau of Meteorology (BoM) in September 2020.
The year commenced with much of the basin affected by drought.
The report said active storage in the River Murray system was relatively low at 3080 Gl (34 per cent).
In January 2020, extreme heat and widespread bushfires were observed for much of eastern Australia, and about 56 per cent of the upper Murray catchment area was burnt.
From February these extreme conditions began to abate, and rainfall returned to much of the northern and southern basin across autumn.
Across the year, Bureau of Meteorology records showed much of the basin received average or above average rainfall with an area-average rainfall of 517.8 mm (long-term average 492.6 mm). This ranks 2020 as the basin’s 42nd wettest year, out of 121 years of data.
While La Niña helped bring welcome relief in 2020, rainfall across the longer three-year period (2018-2020) remains below average to very much below average. Although 2020 brought welcomed rainfall improvements, active storage in the River Murray system remained below the long-term average, peaking in November at 5200 Gl (62 per cent, Figure 1). Elsewhere in the southern basin, storages also increased, with a notable improvement in the Murrumbidgee system bringing total storage above 80 per centby January 2021.
Maximum temperatures in 2020 were also above average across much of the basin. Minimum temperatures were average across much of the southern Basin, but above average across much of the northern basin.
For the whole of Australia, spring 2020 was the warmest on record in terms of mean temperature.
At the end of December, annual inflows into the Murray River for 2020 (excluding Snowy, Darling, IVT and environmental inflows) were about 5700 Gl (long-term annual average of 8800 Gl, the MDBA report found).
34°C