The Bureau of Meteorology is forecasting round after round of rain this week.
Widespread heavy rain is expected all the way from the far north through to Tasmania.
By Friday night the bureau is expecting widespread falls of more than 50 millimetres for parts of southern inland Queensland, much of New South Wales, northern Victoria and northern Tasmania, with even more rain expected over the weekend.
According to forecaster Jonathan How, significant rain and storms are expected to move over the eastern states from late today.
"Showers and thunderstorms will increase, particularly over southern South Australia (including Adelaide), and extend into north-west Victoria and the New South Wales South Coast," he said.
But tomorrow is expected to be the first big peak of rainfall for inland areas as the rain is expected to move further east into Queensland, central NSW, South Australia and Victoria, with widespread showers and storms peaking in the afternoon and evening.
Moderate to major flooding is expected in already flooded rivers in NSW, Victoria, and possibly Tasmania and southern Queensland, according to Mr How.
Conditions are expected to temporarily calm on Thursday before a cold front moves over southern South Australia on Thursday evening and makes its way west.
Mr How warned the storms would intensify again during Friday over southern Queensland, central and eastern NSW, central and eastern Victoria, and northern Tasmania as this next round sweeps through.
But it does not end there.
Heading into the weekend, a low-pressure system is expected to form, dragging yet more showers and rain across southern Queensland and much of NSW.
"Many communities that recently experienced flooding or are currently in flood will likely see rivers rise in the coming week including inland and western areas of NSW, before moving to the ranges and eastern NSW districts towards the weekend," Mr How said.
"The ground remains saturated, and any additional rainfall will cause streams and rivers to rise."
Prepare for floods
All this rain is obviously not good news for already flooded regions.
NSW SES spokesperson Adam Jones warned that with the ground as wet as it is, we could see flash flooding as well as the intensification of the ongoing riverine flooding.
"We're asking the community to make some sensible, smart decisions," he said.
"We're getting ready, we're preparing our crews out there who are already [there]; we're setting a plan up to be able to rotate them through.
"We're asking the community to do the same thing; get themselves ready, make sure they have a plan, make sure they know their risk, make sure they're paying attention to the radio and any messaging that's been put out."
It is messaging that could sound a bit different this year.
A new national warning system is rolling out for floods, like there is for bushfires.
The three-tier system has advice, watch-and-act and emergency level warnings, within which there will be flood and situation-specific action statements.
To check on the latest updates to warning systems, check your state or territory emergency services website.
The state and territory websites are also a good place to start when identifying your risk and coming up with a plan.
Travel safe
With school holiday road trips in the mix, Mr Jones said the key was to be sensible when travelling.
"It's really important that you're paying attention to the weather, paying attention to where you're going.
"Jump on livetraffic.com, make sure you can actually get through," he urged.
He called for patience.
"It might be worth chucking a couple of extra bags of chips, maybe download a podcast or some extra games that the kids can play, in case you do have to get diverted.
"If you can pull over, let the hazard dissipate and then be able to go through, you could save your life and save the lives of our rescuers having to come get you if something went wrong."
