A "bomb cyclone" has lashed Australia's most populous state with heavy rain and strong winds, forcing airlines to cancel domestic flights and prompting evacuation warnings in coastal communities.

A rapidly intensifying low-pressure system known as a “ bomb cyclone ” is lashing Australia ’s eastern coast with torrential rain and winds of up to 110 kmph, raising fears of flash floods, coastal erosion and major transport disruptions.

The low-pressure system that lashed NSW with 110km/h winds and heavy downpours has been forecast to worsen on the South Coast.