Communities rally as floodwaters rise, schools close

The search continues for a woman swept away in floodwaters as rubberneckers worsen the damage for drenched residents.

Scores of communities spent Monday mopping up and replacing roofs after wild weather battered Sydney and northern NSW over the weekend.

More than two dozen schools were shut on Monday across the state's mid-north coast, Hunter and central coast including Kempsey High School where the main building roof was tossed into trees.

Almost 60 warnings were in place on Monday afternoon including evacuation notices for residents in some areas of Gunnedah near the Namoi River.

The local mayor said her biggest concern was people not staying away from the floodwater, including drivers going down town streets and "continuing to put waters back on (residents') houses".

"It's very unfair when people are flooded in," Gunnedah Shire Mayor Colleen Fuller said.

The police community and youth club offers a program for children who cannot attend school, local MP Sarah Mitchell told AAP.

"It's tough, and obviously we think about people who are impacted," she said.

"But we also see our community really rally together as well."

Residents and businesses near the riverbank began preparing for potential flooding as rain persisted through the weekend.

"We just sort of have to wait it out," Ms Mitchell said.

"Just hoping the damage isn't too bad and that everyone can get on with cleaning up and back to normal life as soon as possible."

The Namoi River passed the 7.9m major flood level early on Monday, rising to 8.44m by the afternoon ahead of an expected peak overnight into Tuesday.

Wild weather hammered northern NSW across the weekend after floods and snowstorms stranded cars and cut power to homes.

The search continued on Monday for a 26-year-old woman swept into floodwaters in the Hunter region, after the Mini Countryman she was travelling in became stranded in floodwaters north of Cessnock on Saturday night.

The 27-year-old driver managed to get out, but her passenger was dragged away with the strong current, prompting police to repeat calls for people not to drive into floodwaters.

State Emergency Service crews responding to the emergency saved a 40-year-old man who was stuck in a nearby tree due to floodwater.

The man was swept out of the tree but rescuers followed him into the water and pulled him to shore before he was taken to hospital.

Tens of thousands of households spent a night without power as heavy rain, floods and unprecedented snow wreaked havoc.

The SES had received more than 3600 calls for assistance, responding to more than 2200 incidents including 25 flood rescues amid the bad weather.

A severe weather warning was cancelled on Monday ahead of more settled conditions, although riverine rises remain a risk as floodwater moves downstream.

"People in the warning areas should consider enacting their emergency plans - that means knowing where you will go in case you are asked to leave," NSW SES Deputy Commissioner Debbie Platz said.