Evacuation order issued near Grafton - Ninemsn

Residents downstream of Grafton are being ordered to leave their homes as floodwaters begin cutting off all roads between NSW and Queensland.

A flood evacuation order was issued for northern NSW Ulmarra, Cowper and Brushgrove districts shortly before 7pm (AEDT) on Monday.

The State Emergency Service (SES) is telling about 1500 people who live near the Clarence River, east of Grafton, to pack up and leave their homes in the next few hours.

Thousands of people are already cut off by floodwaters in NSW as a volatile weather system tracks down the coast from Queensland.

Motorists are also being advised to delay all travel between the Queensland border and NSW as the Pacific Highway and Bruxner Highway are expected to close later on Monday night.

"Due to the Summerland Way already being closed, there is no way through to the Queensland border from NSW," said a spokeswoman for the NSW Transport Management System.

A landslip and fallen trees have already closed the Gwydir Highway, while the Bangalow Road is closed between Bangalow and Lismore.

The Bruxner Highway is shut west of Tenterfield and the Pacific Highway closed near Spring Street in South Grafton.

"There is also localised flooding in parts of Sydney and Newcastle, so motorists are advised to exercise extreme caution," the spokeswoman said.

NSW police on Monday night urged motorists to reconsider their travel plans and delay their trips where possible.

"Heavy rain, strong winds and reduced visibility is causing crashes and causing lengthy delays," police said in a statement.

"Motorists are asked to check on weather conditions and road closures and to delay trips where possible."

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