Eastern Australia storms: three dead and more missing as wild weather hits coast

While emergency workers were trying to work out how to rescue the man, his four-wheel drive was swept away by the flood waters and flipped over.

The man’s body was spotted later on an island in the middle of the river.

"The flood waters yesterday ... were extremely strong, savage, with a lot of debris, large logs coming down the river,” ACT police sergeant Harry Hains told reporters in Canberra. "The force was enough to flip a two-tonne ute.”

Police and emergency workers again warned people not to drive through flood waters for any reason.

"These types of weather conditions, extreme weather conditions we’ve experienced, do lead adventure-seeking type people to seek mud with their four-wheel-drives,” Hains said.

"There is no risk worth taking to cross a flooded river to go and seek some piece of dirt to drive your four-wheel drive on.”

Tasmanian police held grave concerns for two elderly people missing as heavy rain drenched the island state.

Search and rescue specialists were searching in Ouse on Monday after reports that a man in his 80s may have been swept away by flood waters.

Another elderly man was rescued from his Latrobe home earlier on Monday morning by helicopter as water inundated his home, but his wife was missing.

More than a dozen people in Latrobe and its surrounds were evacuated by boat, including a family of three rescued from the roof of their car.

Significant livestock losses were reported at dairy farms along the Mersey river.

The Latrobe mayor, Peter Freshney, said the army had been called in to help with the "unique” flooding conditions.

"Even since the 1970 floods, there’s been so many changes to the topography and the like that we really don’t know what we’re facing,” he said. "We’re doing everything we can and all the resources are being thrown at it that we can muster.”

All Tasmanian river basins were on flood watch after parts of the state were drenched with more than 200mm of rain.

A Bureau of Meteorology forecaster, Anna Forrest, said the heavy rains would not ease until Tuesday and wet weather was forecast for the rest of the week.

The Emu river and North Esk river had burst their banks and others were at risk of overflowing. Major flood warnings were in place for the Forth, Meander, Mersey, North Esk, South Esk and Macquarie rivers and a minor flood warning for the Derwent.

The Meander river was expected to peak at between 3.4m and 3.7m at Deloraine by Monday afternoon.

The SES rescued several people in the state’s north and north-west overnight, after they became stranded trying to drive through flood waters amid lashing rain.