Emergency services will decide later today whether to continue searching for a missing American tourist after rough seas have hampered their efforts.

Up to 50 people were searching for the 23-year-old washed off rocks with another American tourist, also 23, on the NSW central coast on Monday, police said.

A Westpac rescue helicopter winched one of the men to safety an hour after the pair were washed into the ocean off Snapper Point, near Lake Macquarie, about 12.40pm (AEST) Monday.

Extensive searches of the area have failed to find the other man.

The rescued man was treated for hypothermia at Newcastle's John Hunter Hospital and released.

Police said rescuers were searching the area by land and sea, but were being hampered by rough conditions.

"Conditions and the location are not suitable for the police divers," the spokeswoman said.

"A decision will be made at three o'clock today whether to continue the search. They put a time (limit) on it to make a decent amount of time to search."

The search involves the Newcastle rescue search coordinators, Marine Area Command, Polair, local police, State Emergency Service (SES), Central Coast Rescue and the National Parks and Wildlife Service.