One of the wettest summers on record continues, with heavy rain forcing a new evacuation order for Lismore in northern NSW amid fears the city is headed for further inundation.
"Everything's falling apart in Lismore at the moment," the city's Mayor Steve Krieg told the Nine Network on Wednesday morning.
"Our river is normally about eight metres lower ... We're estimating in about half an hour to an hour that's going to come up over the levee and the Lismore CBD ... will be inundated with water again.
"So, second time in a month.
"I'm going to jump in my car and get to higher ground."
The Wilsons River is expected to burst its levee on Wednesday morning, peaking over major flood levels of 10.6 metres, up to 11 metres and higher, the Bureau of Meteorology said.
The worst could be yet to come, with further river rises at Lismore still possible on Wednesday afternoon.
City centre residents along with those in surrounding Lismore Basin, East Lismore and Girards Hill have been urged to leave immediately.
Byron, the owner of a petrol station in Murwillumbah, said his business had been flooded in the most recent catastrophic event in the Northern Rivers.
"It came up to like two metres (high) in the shop and we've lost everything," he said.
The recent floods had broken the business' petrol pumps, ovens and fridges which had all since been replaced.
The evacuation order is the second for the city in 24 hours after an all-clear was issued to return with caution on Tuesday afternoon.
Six evacuation orders are in place across NSW for areas including the Lismore CBD, Lismore Basin, low-lying areas of East Lismore, North Lismore and Girards Hill, Riverside Caravan Park Coraki, Tumbulgum, low-lying parts of Kyogle, parts of South Lismore, and Bellinger River Tourist Park on the north coast.
Flash flooding in the CBD as a result of heavy rainfall has inundated roads and an evacuation centre has again been set up at Southern Cross University.
Further south, heavy rainfall and thunderstorms which could lead to flash floods with the possibility of dangerous and life-threatening conditions is forecast for parts of the the Mid North Coast and the Northern Tablelands.
Six-hour rainfall totals between 80mm and 140mm are possible, while up to 300mm may fall over mountainous coastal areas.
Locations in the warning zone include Grafton, Coffs Harbour, Port Macquarie, Taree and Dorrigo.
Alstonville recorded 355mm of rain from 9am on Tuesday, while Bellingen received 276mm, Dorrigo 262mm and Coffs Harbour 207mm.
© AAP 2022