Hopes of finding an American tourist washed off rocks into the ocean are fading, with no sightings so far today as rescue teams battle difficult weather conditions.

A police spokeswoman said the search would continue and the situation would be assessed again tomorrow.

About 60 people were involved in the land, sea and air search, including the State Emergency Service, Volunteer Rescue Association, National Parks and Wildlife Service and Marine Area Command, she said. It was too rough for divers.

Acting Inspector Tony Long said earlier: "As the hours progress - and it's 24 hours since the gentleman went into the water - there are now grave fears for his life."

The man and another male American, both 23, were at the northern side of Snapper Point, near Lake Macquarie, about 12.40pm yesterday when they were washed into the ocean, police said.

One of the men was winched to safety about 1.30pm, and was treated for hypothermia at John Hunter Hospital before being released.

A search for the other man had to be called off at 5.20pm yesterday due to darkness.

The search resumed today at 7.30am, but there have been no sightings of the missing man, acting Inspector Long said.

Rescue efforts were being hampered by the weather, he said.

"The weather is poor, the swell is relatively high and the conditions are generally poor and impacting our visibility."

The difficulty for the searchers was that they were unable to get too close to the rocky coastline, for safety reasons, but visibility was poor from a distance due of the stormy weather, acting Inspector Long said.

The search was focused along "several kilometres of coastline", he said.

The two Americans had been with two women when they were swept into the ocean, he said.

"They were down there with two female friends and they were just sight-seeing," he said.

"It's quite a picturesque area on most occasions and I'd suggest they were taking advantage of that."

However the weather yesterday had been "dreadful", with large waves bashing the rocks, he said.