Weatherzone meteorologist Brett Dutschke said coastal areas between Mackay and the Gold Coast would be most affected by the approach of Cyclone Ului.

The Category 4 cyclone is still 1300km northeast of Mackay in the Coral Sea and is approaching the Queensland coastline at about 5km per hour. It is not expected to cross the coastline.

Despite uncertainty about its future movements, dangerous surf is expected thanks to the fact Ului will have spent about a week out in the Coral Sea, most of it in a very intense state.

"The most guaranteed impact is beach erosion by the weekend," said Mr Dutschke.

"Parts of the coast are likely to see an increase in wind and swell heights as well as heavy rain."

Sunshine Coast surfers are bracing for some of biggest off-shore swells in a decade.

"The burning question is: how close will it get?" said Ben Matson from swellnet.com.au.

"We are confident we'll see big swell between three and five metres. If the cyclone gets closer we could see exceptionally large swell well in excess of five metres.

"Not many surfers would be willing to take on these waves."

Gold Coast lifesaver Steward Hogben urged caution as authorities continue to search for a kayaker who vanished off Hope Island yesterday afternoon.

"At the moment we are keeping an eye out for warnings by the Bureau. Deciding what beaches will be closed is a day-to-day decision," Mr Hogben said.

"We are pleading to people to really think about it."

"If people do go into the water they are not only risking their own lives but that of lifesavers as well. It is for the highly experienced only and is not recommended for the inexperienced."

Mr Matson agreed novice surfers should be wary.

"[These waves] suit fit surfers who ride surfboards designed for big waves, or tow-in surfers who tackle big waves with the help of jet skies," he said.

Noosa Heads and the Gold Coast's northern beaches are likely to be amongst the worst hit areas.

"Kings Beach on the Sunshine Coast will be protected but east facing beaches on the Gold Coast such as from Burleigh to Southport are expected to be affected badly," Mr Hogben said.

Mr Dutschke said it was impossible to know what impact the cyclone would have.

"It’s a long way off and cyclones can easily change course and direction," he said.

Cyclone Ului is expected to be closest on Saturday.