Thousands without power as severe weather lashes coast

Tens of thousands of people are preparing to spend the night without power as heavy rain, floods and unprecedented snow risk cutting access to parts of NSW.

Between 50 and 100mm of rain drenched parts of NSW's Mid North Coast and northern Hunter on Saturday, with more moderate totals across the coast.

The NSW State Emergency Service responded to 745 incidents across 24 hours, with more than 1000 volunteers assisting affected communities.

Widespread showers would continue to impact east and northeast parts of the state, with riverine flooding likely from late Saturday, the Bureau of Meteorology said.

More than 27,500 homes and businesses are without power due to storm damage, and severe weather is delaying its restoration, Essential Energy said on Saturday evening.

"Residents should be prepared to be without power overnight. Our crews are working to restore power where it is safe to do so," the provider said.

People have been urged to stay at least eight metres away from fallen power lines, power poles and damaged electricity equipment, or 150 metres if any part of the electricity network is covered in floodwaters.

Flood watches are in place for Bandon Grove, Allison Road, Bendolba and Calala on the Mid North Coast, as residents are urged to prepare to be isolated by rising waters.

State Emergency Service personnel have forecasted 24-hour rain totals ranging from 65 to 100mm and possible isolated falls of more than 130mm.

"Rivers are likely to respond fairly quickly to the rainfall that is forecast to continue through the course of Saturday," meteorologist Miriam Bradbury said.

A moderate flood warning is in place for the Peel River around Tamworth, with minor warnings for the Manning and Gloucester, Paterson and Williams, and Myall Rivers.

SES Assistant Commissioner Nicole Hogan said the heavy and persistent wet weather might see roads flooded and impassable.

"We implore the community to never drive, walk or play in floodwater," Ms Hogan said.

Snow was also falling at depths not previously seen at Armidale and Guyra in the Northern Tablelands, with full-day falls up to 50cm thought possible, leading to a warning for residents to stay near shelter.

The SES said black ice on roads was causing dangerous conditions throughout the region, as authorities responded to more than 100 vehicles stuck in snow.

"Trees have fallen across roads and multiple accidents have been reported, with cars sliding off the road and blocking access," it said.

Road crash crews have been pre-positioned and are ready to respond to rescues, but authorities are urging motorists to reconsider unnecessary travel.

"If you do need to be on the roads in areas with snow, drive with caution, always use your brakes gently and drive slowly," Ms Hogan said.

Several parts of the New England Highway were closed in both directions due to snow and ice, as were sections of the Kamilaroi Highway due to flooding, and Wakehurst Parkway.

Damaging wind gusts exceeding 90km/h and large and powerful surf are also forecast, with concerns over coastal erosion and damage to infrastructure.