Sydney NSW weather: More areas on evacuation alert as record-breaking deluge eases and Warragamba Dam spills over - here are the latest warnings in your area

More areas of Australia's largest city are on evacuation alert despite the record-breaking rain bomb beginning to ease - as Sydney's Warragamba Dam reaches full capacity and begins to spill.

Warragamba Dam, Sydney's main supply of drinking water, has started to overflow while several rivers in the Greater Sydney region are expected to burst their banks.

As sunny skies greeted Sydney residents on Saturday morning after a day of heavy rain, those in communities on the city's fringes on and the NSW south coast have been warned to expect flooding from saturated waterways. 

More than a month's worth of rain fell over Sydney, Port Macquarie and Taree on Friday, delaying trains, cutting power and leading to evacuation alerts. 

The NSW State Emergency Service (SES) was involved in more than 70 flood rescues in the Sydney metropolitan area by Saturday morning and had received more than 4,000 calls in the last 24 hours. 

NSW Premier Chris Minns and SES Commissioner Carlene York said major floods are expected for the Hawkesbury, Nepean and Colo river in a press conference on Saturday morning.  

'While it looks like blue skies across Sydney at moment ... it is important to note that flood levels in some of the rivers, particularly in Western Sydney, are continuing to rise and that presents a danger for some communities,' Mr Minns said. 

'There was up to 180mm of rain dropped across New South Wales in some areas, up to 9am this morning, which is a heavy downpour in a small space of time.'

Extensive public transport delays are expected across the city across the weekend and the Richmond, Yarramundi and Windsor Bridges will remain closed until Sunday.

Rescue teams have been working around the clock in difficult conditions since Friday, with Commissioner York asking members of the public to safeguard themselves.

'There have been a number of flood rescues over the period of this event. We have had 152 across the state, 72 just in the metropolitan area,' Ms York said.

'People need to make safe decisions to look after themselves and their families or other people in the car and not drive through the flood waters.'

Ms York said that SES teams are monitoring the overflow out of the Warragamba Dam and said surrounding communities had been alerted on what to do if conditions worsen. 

'At this stage we think the effect of that will be just on those low-lying areas where we have been out with the community, letting them know what is coming and ensuring that they prepare for the waters,' she said. 

Rural farmland is expected to bear the brunt of overflows from the dam but Commissioner York warned that families and businesses in the area should remain cautious.

Warragamba Dam contains 80 per cent of the Sydney's drinkable water and started spilling at 5:45am on Saturday. 

The dam's catchment area covers 9,000sq/km including much of the Blue Mountains and from Goulburn in the south to Lithgow in the north. 

NSW government policy does not allow water to be released from the dam even in the face of significant rainfall which otherwise could have prevented flooding. 

The spill from the dam may continue for up to two weeks, Water NSW warned. 

The SES issued more evacuation warnings as floodwaters continue to rise.

One alert for low-lying areas along Sydney's Narrabeen Lagoon covers people living in Warriewood, North Narrabeen and Narrabeen Peninsula.

'If you remain in the area, you may become trapped without power, water, and other essential services,' the SES' warning, issued on Saturday morning, states.

'It may be too dangerous for NSW SES to rescue you, and buildings may not be able to withstand the impact of flood water.'

Another urgent evacuation warning has been issued for Picton in the Macarthur region after the town's CBD was inundated with floodwaters.

There are 62 alerts still active on the SES website.

In the city's west Penrith recorded up to 167mm of rain overnight, while Terrey Hills and Canterbury saw more than 150mm since 9am Friday.

In the Illawarra, Albion Park was smashed by 190mm while Bellambi, just north of Wollongong, recorded up to 194mm.

Residents from Gronos Point and Cattai were urged to evacuate overnight, as were people living in the low-lying parts of Agnes Banks, Cornwallis and the eastern of Richmond lowlands.

Those living in Chipping Norton and parts of Lower Portland on the eastern side of Hawkesbury were are also advised to leave at 12.35am.

Although rain has eased as clouds begin moving south, the Bureau of Meteorology warned that isolated severe thunderstorms of up to 150mm may redevelop Saturday afternoon for areas from the Blue Mountains to Narooma.

The Bankstown Sport Club, Club Liverpool and Richmond Club are currently serving as evacuation centres. 

NSW SES has warned that people living in the Hawkesbury-Nepean region should expect heavy rain to continue into Saturday and road closures are expected.

Anyone living in Sydney, Wollongong, Nowra, Batemans Bay and Goulburn are advised to stay indoors over the weekend to avoid damaging winds and heavy rain.

In Sydney the rain even began flooding into the Town Hall train station as workers struggled to maintain the area.

In rural areas heavy rainfall has created hazardous driving conditions with boulders, tree trunks and other debris littering highways and roads.

Numerous rivers - including the Hawkesbury, Nepean, Georges, Lower Hunter, Myall, Macquarie and Woronora - have been placed on flood watch.

'With the forecast rainfall, further river level rises and moderate to major flooding is possible from Saturday morning along the Hawkesbury and Nepean Rivers,' the Bureau of Meteorology warned on Friday evening. 

Liverpool and Milperra in southern Sydney could experience moderate flooding from the Georges River from Saturday morning.

Surfers and other beachgoers were also warned to stay 'well away from the surf and surf-exposed areas' due to dangerous conditions, particularly at east-facing beaches.

Scores of community sport teams had their winter seasons delayed with flooded grounds from Wollondilly to the Northern Beaches closed all weekend.

Relief won't be in sight for Nepean and Hawkesbury communities downstream of Warragamba Dam.

Mr Minns advised residents to remain alert and up-to-date with warnings in their local areas.

'It is a volatile event and we need to make sure that we've got the latest information ... but it does require everybody being alert,' he said on Friday.

The heavy rainfall that descended on Sydney is now moving southward through the Illawarra region and into the Canberra area over the weekend. For now the ACT is experiencing moderate rain.

Melbourne can expect light rain with sunny periods over Sunday and Monday, while Hobart avoids the rain despite being cloudy over the weekend.

In the nation’s west, sun is continuing to shine while Adelaide, Darwin and Perth can expect a partly overcast but mostly sunny weekend.

In the Northern Territory and Western Australia temperatures are expected to remain above 30C.