Flooding fears grow as rains hammer nation's north

"Any delay now puts your life at risk," the NT Emergency Service said in an alert early on Friday, warning of property damage, dangerous waters and homes becoming isolated.

It was too dangerous to travel and people should shelter indoors until the all-clear was given.

The Bureau of Meteorology said the river at Katherine Bridge may reach the major flood level of 17.5 metres on Friday afternoon.

The main flood peak is approaching Marion Downs, while major flooding continues upstream at Roxborough and Glenormiston, the bureau said.

The flood risks in the Northern Territory come as a tropical low stationed just off the tourist town of Cairns in far north Queensland is set to move south, although its exact path is uncertain.

The densely populated southeast of the state is now on alert, with widespread falls of up to 150 millimetres expected to fall over a 36-hour period between Saturday night and Monday morning, including in Brisbane.

Bureau of Meteorology senior meteorologist Dean Narramore said there was a potential for flash flooding.

The tropical low would weaken as it moved south and into inland Queensland, he said.

"It's going to drag all of that moisture down into much of northern and eastern Queensland, and we're then going to have a high upper trough come into southwest Queensland," Mr Narramore said.

"That's going to tap into that moisture and drag it down into southeast Queensland as we enter Saturday night and into Sunday morning."

SEQWater said in a statement it was closely monitoring dam levels, rainfall and inflows into the dams.

There have been huge totals across the far north, with 467 millimetres falling in a 24-hour period in Yandill, north of Cairns, while Daintree Village had 292 millimetres.

In other areas, sandbag stations are in place with heavy rain, flooding and damaging winds forecast on Friday.

Local infrastructure has already been impacted with the wild conditions causing the Daintree Ferry to come loose from its moorings.

Council and emergency crews will attempt to retrieve the vessel once conditions allow, Douglas Shire Mayor Lisa Scomazzon said.