Between 30 and 50mm of rain drenched parts of eastern NSW on Saturday, leading to 750 calls for assistance to the State Emergency Service.
"Widespread showers will continue moving northeast on Saturday, impacting the Coffs Coast, Mid North Coast, Upper Hunter and New England regions, the Bureau of Meteorology said.
Snow was also falling at depths not previously seen in the state's Northern Tablelands.
State Emergency Service personnel issued 28 warnings across impacted areas, with 24-hour rain totals ranging 65-100mm likely and isolated falls exceeding 130mm possible.
"Rivers are likely to respond fairly quickly to the rainfall that is forecast to continue through the course of Saturday," meteorologist Miriam Bradbury said.
She said flood watch areas could be upgraded to warnings heading into the night, with one already in place for the Peel River at Tamworth.
SES Assistant Commissioner Nicole Hogan said the heavy and persistent wet might see roads flooded and impassable.
Crews had been door-knocking in low-lying areas of Tamworth and warning locals of flooding and coming road closures, she said.
"We implore the community to never drive, walk or play in floodwater - if you come across a flooded road, turn around and find an alternative route," Ms Hogan said.
Unusual snow levels were reported at Armidale and Guyra in the Northern Tablelands, with full day falls up to 50cm thought possible and 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 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.
The New England Highway was closed in both directions between Moonbi and Bendemeer, between Armidale and Glen Innes and between Kentucky and Uralla due to snow and ice.
Damaging wind gusts exceeding 90km/h and large and powerful surf are also forecast, with concerns over coastal erosion and damage to infrastructure.
Ms Hogan said more than a thousand SES volunteers have been activated to respond to the increase in calls this weekend.
6°C