Violent winds toppled power lines on Friday as a tropical cyclone inched towards Australia's eastern coast, sparking evacuation orders and leaving more than 50,000 homes without electricity.

Tropical Cyclone Alfred was 165 kilometres east of Brisbane city on Friday morning, crawling towards the densely-populated coastline at "walking speed", government forecasts said.

Some four million people were in the firing line along a 400-kilometre stretch of coastline straddling the border of Queensland state and New South Wales.

It is a region rarely troubled by typhoons - it has been more than 50 years since a tropical cyclone made landfall in that part of Queensland.

More than 50,000 homes were without power on Friday morning as damaging winds brought down power lines, officials and utility companies said.

Queensland Premier David Crisafulli said the storm already "packed a punch", warning conditions would get worse as it approached land late on Friday or early Saturday.

Emergency response officials said they had issued evacuation orders for some 10,000 people in the flood-prone northern rivers region of New South Wales.

There was particular concern for the town of Lismore, which was engulfed by record 14-metre floodwaters after heavy rains in 2022.

Many residents have spent the past three days fortifying their homes with sandbags, tying down loose furniture and stocking up on food and water.

Prime Minister Anthony Albanese said the region should "hope for the best, but prepare for the worst".

"When nature does its worst, Australians are at our best. We rally. We lift each other up. We look out for our neighbours," he told reporters.

Tropical Cyclone Alfred would likely cross the coast "early Saturday morning", the Bureau of Meteorology said, although its path was becoming difficult to predict.

It was forecast to make landfall around 60 kilometres north of Brisbane.

More than 900 schools across Queensland state and neighbouring parts of northern New South Wales were closed on Friday, education department officials said. (AFP)