The Hunter Westpac rescue helicopter winched the two men and two women to safety about 8am Monday.

The four had set off to go canyoning down the Williams River but did not return.

Police said an EPIRB was set off about 11pm before the rescue helicopter pilot reported seeing a light flashing from a remote area of the Chichester State Forest.

A rescue attempt could not be made on Sunday night because of strong winds and the rugged terrain.

A co-ordinated search began at first light Monday morning, and the helicopter crew found three of the canyoners and winched them to safety.

A fourth, believed to have set off to walk and raise the alarm, was rescued a short time later.

Dungog paramedics, Hunter and Central Command officers, Dungog NSW Fire Brigade Rescue and Neil Grant from National Parks and Wildlife Service assisted with the retrieval operation.

A helicopter spokesman said it did not appear the four had sustained any major injuries and were taken to John Hunter Hospital for observation.