Communities in parts of Queensland and South Australia have also been advised to stay on flood watch.

Bureau of Meteorology senior meteorologist Dean Narramore said the severe thunderstorms across SA and parts of Queensland on Tuesday would start to spread to other eastern states by mid-week.

"Severe weather warnings [are] current for heavy rain and damaging winds in SA and thunderstorm warnings also current for parts of Queensland," Mr Narramore said.

"Rain and thunderstorms will move into Queensland and NSW on Wednesday while continuing through eastern parts of SA.

"Severe thunderstorms once again likely and we could see some isolated heavy falls as well as damaging winds and possible large hail with those as well."

On Thursday and Friday, storms are expected to continue spreading across much of Queensland, NSW and Victoria and parts of eastern SA with large hail, damaging winds and heavy to very heavy rainfall in eastern Queensland and eastern NSW.

Across the weekend, 25 to 50 millimeters of rain is expected across much of Queensland, NSW, Victoria, Tasmania and SA.

Mr Narramore said the total rainfall across the "four or five" days could total between 50 to 100 millimetres across the eastern states alone.

"Now anticipation of this we have flood watches current for large parts of northern SA, much of southern inland Queensland and a number of rivers on and west of the ranges in NSW that aren't currently experiencing flooding right now," he said.

In NSW, Barwon and Darling Rivers, Macquarie River, Bogan River, Lachlan River, Murrumbidgee River, Murray River have also experienced flooding since 7am Tuesday.

In Victoria, Wimmera River, Avoca River, Loddon River, Campaspe River, Goulburn River, Seven Creeks, Broken River, Murray River have experienced flooding since 7am Tuesday.

Communities in Echuca and Moama, Shepparton, Horsham, Kerang, Warren, Euabalong, Hay, and Tilpa can also expect, if not already experiencing, major flooding.

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And if the immediate wild weather forecast wasn't enough, the Bureau also released its predictions for a 73 per cent chance of above-average tropical cyclone activity in Australia in the coming seasons.

Australia's long-term average in the season ahead is 11 tropical cyclones, but the 2022 to 2023 period will likely exceed this for the first time since the 2005-2006 season.

The forecast is based in climate drivers including a La Nina system and a natural climate phenomenon that influences weather patterns around the Indian Ocean, known as Indian Ocean Dipole (IOD).

Both are associated with warmer ocean temperatures near Australia which means more moisture over the continent and stronger low pressure systems in the south.

For now, communities are advised to stay alert amid this week's storms.

"Residents living on or near any rivers, creeks or streams or low line areas through New South Wales or Victoria are reminded to stay up to date with the latest forecasts and warnings via our website, app and social media," Mr Narramore said.