Ex-cyclone Seth to cross Qld coast

Ex-tropical cyclone Seth is set to cross the Queensland coast but is weakening, with only heavy rain forecast for the state's southeast in the coming days.

The system had created massive swells along the coast this week with the body of a boogie boarder found in the surf off the Gold Coast on Wednesday.

But the Bureau of Meteorology says the former cyclone has already "detonated" and will peter out when it finally reaches land on Friday, ensuring heavy but isolated showers for the southeast.

The Wide Bay area north of Brisbane is expected to be hit with heavy rain when the system crosses the coast near Fraser Island, with Gympie and Kingaroy to cop up to 60mm of rain.

Isolated showers have also been forecast for the Sunshine Coast and Gold Coast in the coming days.

"By the time it hits the shore at Fraser Island it would have weakened until it is just a low," BOM atmospheric scientist Brooke Pagel told AAP.

"We are just looking at heavy, localised rainfall.

"Even now while it is off shore it is just falling apart. It has detonated at this point so there will be just lots of rain with that one."

Ex-tropical cyclone Seth moved toward the Gold Coast, prompting this week's hazardous surf warnings but has slowly travelled northwest to be off Fraser Island on Thursday afternoon.

Strong wind warnings for coastal areas from Fraser Island to the Gold Coast have been issued for Thursday and for the Sunshine Coast on Friday.

"They are for all the boaties. There are no land wind warnings at the moment," Ms Pagel said.