A powerful weather system is set to bring widespread rain and storms to parts of southern Australia this week, with some already saturated catchments facing renewed flooding risks.

The weather pattern is expected to intensify from Monday, with South Australia among the first areas to experience heavier falls. Forecasters say parts of the Eyre and Yorke peninsulas, along with the Adelaide Hills, could record between 30 and 50 millimetres of rain in some locations.

While the rainfall will provide valuable moisture for some agricultural areas, conditions are becoming a concern for communities where soils and waterways are already saturated.

The focus will shift east on Tuesday, with north-east Victoria and southern New South Wales expected to receive some of the heaviest falls. Rain totals of 40 to 60 millimetres, or potentially more, are possible across areas that have already experienced significant rainfall.

Meteorologists warn that the additional water could trigger further flooding, particularly in catchments that have had little opportunity to dry out.

Rain is also expected across parts of the Murray-Darling Basin and southern South Australia, although totals in these regions are likely to be lower.

Further east, showers and thunderstorms are forecast to continue across eastern New South Wales and southern Queensland as the weather system moves offshore.

Western Australia will experience a different pattern, with frost possible across southern areas before showers develop along parts of the coast.

The unsettled conditions are expected to continue through the latter part of the week. Another low-pressure system developing in the west could bring additional rain to Western Australia’s south coast, while a weaker cold front may affect Tasmania and southern Victoria later in the week.

Authorities are urging residents in areas prone to flooding to monitor official weather warnings and remain alert as conditions change.

The latest system comes as Australia heads towards the more active storm season, highlighting the need for communities to prepare for rapidly changing weather conditions.