NSW Emergency Services Minister David Elliott has slammed "boofhead behaviour" and urged people to heed safety warnings as the deluge of rain continues across the state.

Key points: The weekend could see top falls of 200mm along the coast as a trough deepens on Saturday

The weekend could see top falls of 200mm along the coast as a trough deepens on Saturday Flood risk-prone areas include Penrith, Colo River and parts of the South Coast

Flood risk-prone areas include Penrith, Colo River and parts of the South Coast Conditions are set to ease on Monday with lighter showers forecast next week

The State Emergency Services (SES) has responded to more than 3,250 calls since the start of the wet weather, with more than 500 of those occurring last night, as the state continued to be lashed by rain.

"That says to me the community is just not taking seriously some of the warnings that have been issued," Mr Elliott said.

"I would appeal to the community to be very conscious of the fact that drains, rivers and any number of pieces of infrastructure will be challenged over the course of this flood activity and, of course, that's been made even worse by the king tides."

David Elliott urged the public to follow SES advice. ( AAP: Bianca De Marchi )

Mr Elliott heavily criticised an unidentified man who was filmed riding a jet ski down a street in Tuggerah.

"With this sort of boofhead behaviour, we're not going to tolerate it as far as the police are concerned," he said.

"We have emergency services deployed during a difficult job under difficult circumstances, and for them to have to divert their resources because people want to hand it out at a time when families are at home worrying about their well-being, and certainly the families of the emergency services workers are worried about their well-being, it's just not good enough."

Bureau of Meteorology (BOM) forecaster Diana Eadie said 320 millimetres had fallen at Cujurra Creek in the state's far north-east, but as the system moved south other areas would be affected.

"The focus is going to be central parts of NSW, including the Sydney area," she said.

"We're expecting 120mm to 200mm [in Sydney] and hundreds of millimetres across much of the Central Coast.

"At the same time, we're also going to see a deepening of the coastal trough that's been bringing this significant rainfall."

Ms Eadie said damaging winds would average around 65 kilometres an hour, with gusts of up to 90kph.

"And we're also seeing some very large waves developing, up around 5 metres in the surf zone, and abnormally high tides as well," she said.

On Saturday BOM acting state manager Jane Golding said those winds would generate large, powerful rains in combination with king tides which could lead to significant coastal erosion.

"This is a very dangerous system … It isn't something we see that often," she said.

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BOM has issued a severe weather warning for much of the east coast, with the potential for "life-threatening" flash flooding tonight in areas from Coffs Harbour to Ulladulla.

The BOM said five-metre waves could hit along the coastline on Sunday from Forster down to the South Coast.

BOM senior forecaster Jenny Sturrock said there was concern for flooding into Batemans Bay on Sunday.

"Obviously we've had people evacuated to Batemans Bay recently with the fire activity, so we do understand that there will be some potentially extra vulnerable scenarios where people are in temporary housing, caravans or tents," she said.

"With that storm surge coming through pushing high tides, it does exacerbate those flooding conditions of the low-lying coastal areas."

James Purshouse (L) and Jock Tudgey on Jock's property in Newhaven celebrate the wet weather. ( AAP: Peter Lorimer )

Some outdoor events were cancelled due to extreme weather conditions, including the A-League derby between Sydney FC and Western Sydney Wanderers at Kogarah Oval has been postponed.

Heavy rain and severe flooding also forced the cancellation of Saturday's Inner West Summer Fest at Enmore Park and the Red Hot Summer Tour shows which were meant to take place on Saturday and Sunday on Cockatoo Island.

"The site has been deemed unsafe and we are unable to complete the build despite every attempt of our crews working around the clock to do so," organisers said.

"We are as devastated as you all are."

We may already have had plenty of rain, but there's more on the way. ( Supplied: BOM )

The State Emergency Services (SES) is asking people in affected areas to be vigilant and monitor for flash flooding.

"People should leave low lying areas before flash flooding begins is the best action you can take," said SES spokesperson Ilana Pender-Rose.

"If you're trapped by rising flood water you can seek refuge in the highest part of a sturdy building."

People are being urged not to walk, ride or drive through rising floodwaters.

Parents should also keep their children away from creeks, drains, gutters and streams.

"Not only is it incredibly dangerous but it can also contain debris and sewage," Ms Pender-Rose said.

"Just 10 centimetres of water can float a small car."