Cyclone Debbie could cost the insurance industry more than $1 billion, Insurance Council of Australia chief executive Rob Whelan has warned.
About 7,500 claims worth hundreds of millions of dollars had been lodged by Queensland residents by Friday lunchtime, Mr Whelan said.
But he expects that figure to rise given the severe flooding in the northern NSW city of Lismore, with Suncorp, Insurance Australia Group and RACQ Insurance particularly exposed.
"People are only just slowly returning to their properties to get an assessment of the level of damage so we expect that to escalate quite quickly," Mr Whelan said.
Mr Whelan said it was possible that claims could pass $1 billion because of the flooding in Lismore.
"The township is heavily flooded now, which hasn't happened for a long time," he said.
Ratings agency Standard and Poor's said on Friday that net claims against insurers from cyclone Debbie are likely to be manageable and below the $1.3 billion stemming from cyclone Yasi in 2011.
S&P also said it expected insurers would manage claim impacts well due to strong capital positions and adequate reinsurance cover.
Cyclone Debbie hit Queensland's Whitsunday coast as a category four storm on Tuesday, and wreaked havoc on towns including Proserpine, Bowen and Mackay.
The storm travelled south as a tropical low, leading to serious flooding and mass evacuations in south-east Queensland and as far south as northern NSW - where there are fears that people have died.
Mr Whelan said the damage from cyclone Debbie is the worst since Cyclone Oswald in 2014, when storms and flooding affected large parts of Queensland and NSW - causing insurance losses of almost $1.2 billion.