By Farid Farid in Sydney

A heavy burst of more than 100mm of rainfall over three hours in Sydney has led to flash flooding, sparking evacuations and rescue operations.

There were 42 rescues overnight, with more than 250 personnel across the city responding to about 500 calls for assistance, particularly in the south-west, NSW State Emergency Service said.

It was especially severe in Fairfield, about 30km from the city centre, where six people were rescued after becoming stranded by rising floodwaters on Vine Street.

A few streets over, about a dozen properties were evacuated due to floodwater inundating homes on Spring Street.

Thousands of commuters were stranded on major arterial roads, including Anzac Bridge, and parts of Parramatta Road were closed.

The Bureau of Meteorology said more rain was expected on Friday but it is easing ahead of the annual Mardi Gras parade, where thousands of revellers will celebrate in Sydney’s city centre on Saturday.

About 15-70mm of rain is forecast for Friday and thunderstorms are also expected.

Other parts of Australia have also been deluged. The remote town of Birdsville in southwest Queensland received nearly 60 per cent of its annual rainfall of 161mm in one day after 93mm of rain fell.