Heavy and persistent rain on the NSW mid-north coast has prompted flash flooding warnings, with some areas receiving more than 300 millimetres since the drenching began.
Carey's Peak, in the upper Hunter region, copped 339mm in the 36 hours to midday Thursday, while the town of Dungog received 287mm over the same period.
Schools in Dungog, where three people died during the 2015 floods, were closed on Thursday as a precaution.
The NSW SES is tracking 850 calls for help statewide, mostly in the Hunter and Lake Macquarie region since Wednesday where residents are mopping up.
Five vehicles have been pulled from floodwaters in the Hunter Region, SES spokesman Phil Campbell told AAP.
Residents on the mid-north coast, where much of the activity will be focused on Thursday, have begun to report minor damage such as leaking roofs and fallen trees or branches.
Mr Campbell said volunteers were also helping with a small amount of sandbagging.
The Bureau of Meteorology issued a severe weather warning for the Mid North Coast and parts of the Northern Tablelands and urged residents to be wary of flash flooding on Thursday and Friday.
"Rainfall may lead to local and riverine flooding is expected over the Mid North Coast from Bulahdelah to Coffs Harbour," BOM said.
BOM forecaster Zhi-Weng Chua said the rainfall was being driven by a coastal trough.
"That combined with some strong onshore winds that were moist and unstable led to very persistent and heavy rainfall," he told AAP.
"There were some storms mixed in with these showers as well."
The system will move gradually north, however it should begin to easy on Friday.
Drivers are encouraged to slow down, take extra care and avoid driving in floodwaters.
