Much of Australia's eastern coast remains underwater as torrential rain continues to hit rural areas, causing more floods and evacuations, foreseeing a wet Christmas for many Australians, authorities said on Friday.

Four deaths have been recorded so far as the nation's east has been suffering its worst flooding in decades, ruining crops and causing millions of dollars of damage.

Forty-eight disaster areas have been declared across the nation.

There were fresh evacuations in Victoria's northeast, with about 60 people forced from their homes in the Alpine Shire local government area, 300 km northeast of Melbourne.

Rain moving northeast from New South Wales (NSW) was forecast to hit Queensland during the next 72 hours from Friday.

The central Queensland city of Rockhampton is braced for flooding over the weekend, as were other parts of the state.

The Weather Channel's senior meteorologist Dick Whitaker said there would be flood peaks along the Fitzroy River basin in central Queensland, the Balonne river in south-eastern Queensland and Barcoo river in western Queensland.

"This will mean a wet, rather than white Christmas for many in outback Queensland," he said.

The NSW State Emergency Service also warned of Christmas evacuations.