Sea foam has covered the beach along the coast of Port Macquarie in New South Wales in Australia, as flooding caused by the remnants of a tropical cyclone continued across some areas of the state in Australia.

The sea foam phenomenon swallowed up the beach in Port Macquarie, where some people decided to go swimming and playing in foamy ocean.

"It's fun to play in but it's never been this bad. We've always had foam when it gets wild, but it's never been this far up before," said Erin Smith, a Port Macquarie resident.

The foam is created by impurities in the ocean churned up together by powerful currents, which cause the water to form bubbles.

Elsewhere, across the Queensland coast, the foam covered roads in places, causing traffic to be diverted.

Meanwhile, according to local officials, Port Macquarie was at risk of flooding, but the risk of a disaster dropped as the rain eased.

The current flood crisis was not as severe, though some areas in northern New South Wales were hit by more than half a metre of rain, State Emergency Services Deputy Commissioner has said.

Four people have died, including a three-year-old boy who was hit by a falling tree in Brisbane.

Australia has been suffering through a summer of weather extremes, with blistering temperatures and dry conditions igniting hundreds of wildfires across the southern half of the country.