The state's flood crisis entered its 75th day on Monday as a severe storm warning was issued, affecting the NSW Mid North Coast through to the New England region in the west.
A trough and unstable airmass created the severe thunderstorms, which could lead to large hail, heavy rainfall, flash flooding and damaging winds on Monday afternoon.
The warning area includes Port Macquarie on the coast, Kempsey and Comboyne, and extends west to Walcha, Uralla, Armidale and Barraba.
It comes after severe storms battered parts of Sydney, the Central Coast and Wollongong on Sunday night.
The State Emergency Service received 100 calls for help in the 24-hours to Monday morning - 30 of them in the Sydney metropolitan area - mostly for trees or branches falling on homes and driveways.
There are 68 flood warnings across the state - 12 of them at emergency level.
The SES flood assistance effort remains focused on the western NSW town of Euabalong where the Lachlan River has isolated the town.
Euabalong publican Neil Quinn said the town last week stared down the swollen river with a hastily-built levee bank holding back floodwaters.
"I don't know how we did it, but we stopped the river," Mr Quinn told AAP on Sunday.
It followed a tense week when the town's original flood bank began to fail and evacuation orders were issued.
Mr Quinn said the town would be relying on helicopters for supplies for at least a month.
The SES is also focused on the towns of Hay, Balranald, Brewarrina, Bourke and downstream towns, Torrumbarry, Barham, Boundary Bend and Moulamein.
