Hundreds of homes inundated in NSW

Hundreds of homes have been inundated in and around Australia's largest city in a flood emergency that was impacting 50,000 people, officials said on Tuesday.

Emergency response teams made 100 rescues overnight of people trapped in cars on flooded roads or in inundated homes in the Sydney area.

Days of torrential rain have caused dams to overflow and waterways to break their banks, bringing a fourth flood emergency in 16 months to parts of the city of 5 million people.

Evacuation orders and warnings to prepare to abandon homes impacted 50,000 people, up from 32,000 on Monday, New South Wales Premier Dominic Perrottet said.

The New South Wales state government declared a disaster across 23 local government areas overnight, activating federal government financial assistance for flood victims.

Parts of southern Sydney had been lashed by more than 20 centimeters (nearly 8 inches) of rain in 24 hours, more than 17% of the city's annual average, according to the Bureau of Meteorology.

Severe weather warnings of heavy rain remained in place across Sydney's eastern suburbs on Tuesday.

The warnings also extended north of Sydney along the coast and into the Hunter Valley.

The worst flooding was along the Hawkesbury-Nepean river system along Sydney's northern and western fringes.