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.

The effect of a "bomb cyclone" around the New South Wales coastline is being felt north, in Queensland. Parts of the state experienced wind gusts averaging between 60 and 70 kilometres an hour overnight. Unlike in New South Wales, it is bringing cold but dry conditions to much of the state that could continue until Monday.

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