The eastern migration of the cold front which earlier in the week buffeted parts of Western Australia with damaging winds and dangerous seas has seen severe weather warnings issued in five states and territories - New South Wales, South Australia, Victoria, Tasmania and the ACT.
Conditions are expected to worsen on Wednesday night into Thursday morning, as a complex low pressure system moves towards the coast.
Heavy rainfall is expected in some regions, with isolated major flooding possible in catchments in southern NSW, northern Tasmania and north-east Victoria.
Minor to moderate flooding is possible elsewhere in the affected areas.
The Bureau of Meteorology is monitoring the situation closely and will update its forecasts and warnings regularly.
Damaging wind gusts of around 90km/h are possible over the ranges west of the ACT, east to Bombala, south to Crookwell and north to Oberon on Thursday morning.
Damaging wind gusts in excess of 125km/h are likely for alpine areas above 1900m on Thursday.
Heavy rainfall with six-hourly totals between 45 and 60mm are possible across the Snowy Mountains and South West Slopes on Thursday.
Severe thunderstorm activity is also possible Wednesday evening into Thursday.
A flood watch for inland NSW Central and South West catchments has been issued with minor to isolated major flooding possible from Thursday.