RELENTLESS storms continue to lash communities in the north of NSW with residents told to prepare for heavy rainfall and possible flash flooding.

Four vehicles were pulled from floodwaters in the Hunter Region yesterday, according to the State Emergency Service, which responded to more than 750 emergency calls.

A severe weather warning remains in place for the Hunter, Mid North Coast and the Northern Tablelands.

"100mm to 200mm is expected in the warning area during Wednesday night and Thursday, with the heaviest falls contracting to the Mid North Coast and the Northern Tablelands," the Bureau of Meteorology stated.

"Some locations are likely to receive more than 200mm in a 24 hour period."

Locations which may be affected include Coffs Harbour, Port Macquarie, Taree, Kempsey, Sawtell, Dorrigo, Nelson Bay, Dungog and Yarrowitch.

Since 9am yesterday Tocal has recorded 124mm of rain, Williamtown 122mm and Maintland 109mm. Dungog recorded 68mm in 1 hour yesterday morning.

Residents of Dungog, where three people died in the 2015 floods, have been issued with flood warnings, an SES spokesman told AAP.

The small town is a "magnet" for this type of weather, bureau meteorologist Ashleigh Lange said.

Alan Smith, of the Settlers Arms Hotel in Dungog, told The Daily Telegraph residents were remaining calm but prepared for the worst.

"The storm water is rising … people are worried after (Dungog's) history of flooding," he said.

"Everyone's keeping an eye on things and are focused on protecting what they can."

The heavy rain is forecast to move north as far as Coffs Harbour before easing on Friday, according to the Bureau of Meteorology.

Flash flooding is possible while gusty winds are also likely to create hazardous surf conditions.

Those driving are encouraged to slow down, take extra care and avoid driving in floodwaters.