Cyclone Marcia is now a category three system, and likely to be further upgraded to category four before it hits the central Queensland coast early on Friday morning.
A 250km strip of the state's coastline between St Lawrence and Gladstone is at risk of a direct hit of the intensifying storm, which was upgraded from a category two late on Thursday afternoon.
The Bureau of Meteorology forecasts it will become a category four cyclone at 3am (AEST) Friday - an hour before it's expected to make landfall just north of Yeppoon.
The weather bureau says it could bring sustained winds between 120-160km/h with gusts of up to 225km/h.
The BOM website says storms in category three can damage roofs and structures, destroy caravans, break boats from moorings and cause power blackouts.
Category four cyclones can feature gale-force winds of up to 260km/h, cause significant roof and structural damage, overturn caravans and trailers, generate dangerous airborne debris and trigger widespread blackouts.
SEQ Water has also advised the Wappa Dam, just inland from the Sunshine Coast, is completely full, meaning forecasted heavy rainfall will significantly swell the Maroochy River.
It said overflows had reached a level where they could pose a safety hazard downstream.
Queensland Premier Annastacia Palaszczuk was briefed by the state's disaster management committee at Kedron, in Brisbane's north, late on Thursday afternoon.
"It is important all Queenslanders brace themselves for heavy rain," she said after the briefing. "This is a serious event.
"It has changed drastically since this morning. It has gone from a category one to a three and we're likely to see category four. Queenslanders need to be prepared now."
