SYDNEY -- Ex-tropical cyclone Alfred lingered off the south-east Australian coast on Saturday and forecasters said Brisbane is likely to miss the worst of the storm, a relief for millions of residents in the region who have been staying indoors.

Alfred, now downgraded to a 'tropical low', crossed the islands off the coast of Queensland overnight, and is heading towards the mainland in the coming hours, the Bureau of Meteorology has said.

Thousands have been evacuated and local media reported that about a quarter of a million people are facing power outages as violent winds toppled power lines. No deaths have been reported but authorities have urged residents to stay indoors and warned of worse to come.

"The impacts are already being felt, and there is worse to come in the hours ahead," Prime Minister Anthony Albanese said in a news conference from the National Situation Room in Canberra.

"Its impact will be serious and will intensify over coming hours and indeed over the coming days, it will still bring strong winds, heavy rain, flooding and dangerous conditions across South East Queensland and North East, New South Wales over this weekend and in the days beyond," he said.

Brisbane and the Gold Coast will be hit with heavy rain today, while the northern New South Wales city of Lismore, among the worst impacted by record floods over the years, has already begun flooding.

Brisbane Airport remains shut and the city has suspended public transport. More than 1,000 schools in southeast Queensland and 280 in northern New South Wales have been closed.

Videos posted on social media and local news networks show some flooding, fallen trees, damaged homes and waves crashing in on the beaches.

Officials have described Alfred as a "very rare event" for Brisbane, the capital of Queensland, which was last hit by a cyclone more than half a century ago in 1974. The city of about 2.7 million had near misses from cyclones in 1990 and 2019.