'Never seen rainfall like this': Fresh flood emergency unfolds

A flood emergency is unfolding in Far North Queensland with residents evacuated and homes going under water.

Five days of torrential rain has turned roads to rivers, cutting off some areas just days after Cyclone Jasper, with more on the way.

Some areas copped more than 400 millimetres of rain in just six hours today, on top of more than half a metre in the past 24 hours.

LIVE UPDATES: Far north Queensland flooding emergency

Rivers and creeks are breaking their banks with Cairns Airport closed for the second time in a few days, a week before Christmas.

Some planes have even gone underwater.

"This is very serious and it could get worse," Premier Steven Miles said.

Miles said 1977 flood levels were expected to be exceeded.

Late last night, he announced the government had sent boats from the State Emergency Services, firefighters, and police, as well as surf life saving and small Navy vessels, to help.

"We've seen rainfall in some places of almost 600 millimetres with more to come," he said.

Miles said locals told him they had "never seen rainfall like this".

The famous Barron Falls is bursting and the Captain Cook and Palmerston highways are underwater.

Backpackers have been stranded, and floating cows were fished out of the river by locals.

Queensland Fire and Emergency Services officers have been called to more than 50 flood rescues.

Deputy Police Commissioner Shane Chelepy warned people not to take risks driving or swimming.

"We've had reports of people swimming and driving into floodwaters - please don't do that, the roadways underneath may be severely damaged," he said.

He said 10,500 homes were without power.

Homes in Innisfail and around the Mossman River have been flooded - some for the second time this week.

Throughout the day and into the evening yesterday, a string of emergency flooding alerts were issued from Cairns up to Wujal Wujal, were Jasper crossed the coast last week.

READ MORE: Girl fighting for life after being struck by lightning in Queensland

The blocked roads also made it impossible for crews to fix blocked water intakes, meaning storage was dwindling.

"We've currently got about 30 hours left so we're urging people to top up on water while they can," Cairns Mayor Terry James said.

After hitting the Queensland coast on Wednesday as a category 2 system, Jasper rapidly weakened into a tropical low as it made its way over the state.

Thunderstorms and heavy rains have continued to batter some areas.

Bureau of Meteorology senior meteorologist Laura Boekel warned of "widespread and continuing rain".

Black Mountain has seen 652 millimetres over 24 hours, with many areas getting more than 300 millimetres.

More than 20 places had more than a metre of rainfall since the cyclone approached, she said.

Another 500 millimetres is possible over the next day.

Financial help was rolled out as the cyclone hit last week.

Meanwhile, south-east Queensland is expecting more storms amid a heatwave, with a girl fighting for life after being struck by lightning on the Sunshine Coast.