The Great Western Highway is re-open in both directions at both Springwood and Mount Victoria.

Fallen trees had closed the highway earlier.

Motorists are still advised to allow extra travel time and drive to the conditions, Live Traffic NSW advised.

EARLIER:

A main road link between Dubbo and Sydney is closed in two places on Sunday as authorities warn motorists to take care in extreme weather conditions.

Live Traffic NSW reports the Great Western Highway is closed both ways in Mount Victoria due to a fallen tree near Harley Avenue.

There is no diversion and the agency has asked motorists to avoid the area.

The Great Western Highway also remained closed in both directions at Springwood due to a fallen tree near Macquarie Road, Live Traffic NSW reported.

There is a diversion via Macquarie Road.

There are also road closures at multiple locations in Sydney's west, north, and south, inner Sydney, and NSW's south.

"A number of other roads and public transport services are affected by the extreme weather conditions across the state, please drive with extreme care and allow plenty of extra travel time," Live Traffic NSW said in a post to Facebook.

Police and emergency services are urging the community not to take risks in the current wet weather conditions being experienced across much of NSW.

The Bureau of Meteorology has issued severe weather warnings including heavy rainfall, damaging winds, abnormally high tides, and damaging surf for the Sydney Metropolitan area, Illawarra, South Coast and parts of Northern Rivers, Mid North Coast, Hunter, Central Tablelands, Southern Tablelands and Snowy Mountains areas.

There is also potential for periods of torrential rainfall and life-threatening flash-flooding in the Hunter region and Central Coast, Sydney Metropolitan areas, the Illawarra and eastern parts of the Central Tablelands, including the Blue Mountains.

Further, Flood Watch and Flood Warnings have also been issued for Byron Bay, Coffs Harbour, Port Macquarie, Taree, Newcastle, Gosford, Sydney, Katoomba, Lithgow, Wollongong, Nowra, Ulladulla, Eden and Moruya Heads.

Deputy State Emergency Operations Controller, Assistant Commissioner Karen Webb, said emergency services are continuing to assist people impacted by recent and current weather.

"During severe weather events, NSW Police are poised to assist the State Emergency Service, and we are currently working with them to minimise the impact of the storms on the community," Assistant Commissioner Webb said.

"There are currently hundreds of calls for assistance, including trees, boulders or power poles down onto cars and homes, and across roads, as well as power outages and localised flooding impacting various roads and traffic lights."

Assistant Commissioner Webb added that police have also responded to or been made aware of incidents resulting from people taking unnecessary risks or displaying dangerous behaviour.

"I'm disappointed that I need to remind people to act responsibly and not to take risks in these types of conditions, especially when around floodwaters," Assistant Commissioner Webb said.