ABOUT 3500 people are isolated on the NSW North Coast as the region is hit with gale force winds, strong rain and flooding.

A severe weather warning is in place in the north, with the weather bureau forecasting very heavy rains leading to flash flooding over the Northern Rivers, Mid North Coast, Northern Tablelands, and the Hunter.

The SES expects the town of Bellingen to be cut off overnight, and says it's already received a thousand calls for help, and rescued three people from a car at Taree.

Emergency crews are also monitoring the Macleay and Clarence rivers, with peaks expected to affect places including Grafton and Kempsey.

Essential Energy also says 33,000 homes are without power in Ballina, Byron, Yamba and Maclean.