State Emergency Service volunteers were called to Rogan Bridge Road at Mylneford, about 20km northwest of Grafton, shortly before 1pm today after a car was seen submerged in floodwaters.

They found the body inside the car and alerted police who are working to identify the man.

Police are urging motorists not to drive into floodwaters following the man’s death and the rescues of at least 15 other people from floodwaters during the severe weather passing down the NSW coast.

The man’s death follows that of a 17-year-old boy who was sucked into a drainpipe on a golf course on the mid-north coast last night.

The boy was collecting golf balls in waist-deep water with friends in the NSW town of Kew before he got swept away.

A friend found his body this morning.

More than 3850 people are isolated on the north coast and the SES has received more than 1570 calls for assistance.

No major towns have been cut off, but the SES holds concerns for the NSW town of Bellingen.

‘‘At this stage we haven’t had any reports of any major inundations but we’re still keeping a close watch on that area,’’ an SES spokeswoman said.

Overnight the SES had to perform 15 flood rescues, most of which they say could have been avoided.

‘‘Many of these rescues relate to deliberate entry into floodwater and the NSW SES urges people not to drive, ride or walk through floodwater,’’ it said in a statement.

Flood warnings have been issued for areas around 17 NSW rivers, with major flood warnings in place for the Clarence River and the Bellinger River.

A moderate to major flood warning has been issued for the Macleay River and residents in the Lower Macleay region have been ordered to evacuate.

‘‘We’ve been door-knocking in the area,’’ the SES spokeswoman said.

‘‘At the end of the day we can’t force them to, but we’re asking that they leave immediately.‘‘

Once we door-knock it’s up to them to go.’’

A severe weather warning remains in place for the mid-north coast, Hunter, Illawarra, Sydney and parts of the central tablelands.

Heavy rain that could lead to flash flooding is predicted for those areas throughout Saturday.Sydney will experience winds of about 50 to 65 km per hour on Saturday evening.

‘‘Along the coast winds are quite strong,’’ a Bureau of Meteorology (BOM) spokesman said.

‘‘There’s also some quite large seas and swell so the surf is quite dangerous and rough.’’‘‘It’s generally pretty wild and woolly out there.’’

The SES has received about 70 calls from the Sydney metropolitan area but says there hasn’t been too much damage around the city.

The bureau says the low pressure system should move south tomorrow morning, easing weather conditions.

The Transport Management Centre has advised NSW residents to avoid travelling on the state’s north coast as severe weather has caused road closures.

The Pacific Highway is closed near Macksville and at South Grafton.

In the Illawarra, all 17 beaches have been closed.

Police were responding to calls about water on the road at Macquarie Pass at 4.15pm and reports a car had spun out of control.

Earlier an accident on the F6 held up northbound traffic near Gwynneville.