Much of NSW has copped the barrage, with 22 flood rescues performed overnight in those areas.
Taree, on the state's mid-north coast, took the worst of the rain with more than 160mm in six hours overnight, and 267mm since 9am on Monday.
"We've seen significant flooding in Taree overnight, a couple of the flood rescues we undertook were for people in houses in locations where water rose incredibly swiftly over their floors and they had to be relocated again, all brought to safety," NSW SES chief superintendent of state operations Dallas Byrnes told ABC TV.
Minor to major warnings for flooding on catchments across the mid-north coast and Hunter regions remain in place, while people in Taree are being advised to take shelter.
The SES has also asked people in isolated locations in the area to evacuate, including at Dungog, Paterson, Gloucester, Bulahdelah and Chinchester Dam.
"We are asking the community to be really, really conscious of their location … we are seeing lots of local creeks rise very quickly," Mr Byrnes said.
"We have had numerous rescues from people entering floodwaters (but) we've also done the majority from people who've just been in the wrong place, and flash flooding has taken them by surprise."
The Bureau of Meteorology is predicting rain levels between 60 to 100mm in six hours on Tuesday in parts of the mid-north coast and Hunter, increasing to 100 too 190mm in isolated locations.
While damaging winds and surf are expected to ease later on Tuesday, the widespread is tipped to stick around for some days.
"Heavy falls will remain a risk, particularly across the mid-north coast, with flash and riverine flooding continuing to be the main concern," BoM senior meteorologist Sarah Scully said.
"With large amounts of water building up over days and impacting roads and low lying areas, dangerous driving conditions, traffic and transport delays and detours are expected, and some local inundations will continue to occur."
More than 30 schools will be closed on Tuesday in the mid-north coast, Central Coast and Hunter regions due to flooding.
The NSW education department reminded parents that schools do not offer minimal supervision during flood events.
Trains are not running between Scone, in the upper Hunter, and Newcastle.
With AAP.
