Insurers are already feeling the pain from ex-tropical cyclone Oswald, with nearly 10,000 claims lodged and the damage bill at $116 million and rising.
Brisbane-based Suncorp, the owner of AAMI and GIO, is set to be the worst affected of the major insurance companies, already fielding about 4,000 claims for flood and storm damage.
Insurance Australia Group, which operates the NRMA Insurance and CGU businesses, said it had received about 2,000 claims.
QBE has fielded 700 claims, and said it expects the final number to be well below those taken after the 2011 Queensland floods.
"We will have further clarity later in the week as people return to their homes and the water subsides," a QBE spokesperson said.
The Insurance Council of Australia estimates about $116 million in claims have been lodged in Queensland to date, and that is set to increase significantly as NSW residents come to grips with flood damage.
"It is still early days and our focus is on assisting customers and we have emergency repairs underway," an IAG spokesperson said.
The insurers said they were financially prepared for the latest natural disaster, given a relatively quiet 2012, meaning there is unlikely to be an immediate impact on premiums.
Shares in two of the three companies fell heavily on the local market when trade resumed on Tuesday after the Australia Day long weekend.
Suncorp shares lost 21 cents, or 1.9 per cent, to $10.70 and QBE dropped 31 cents, or 2.7 per cent, to $11.28.
IAG was down for most of the day but recovered to add one cent to $4.93.
Ex-tropical cyclone Oswald was creating even more uncertainty for an insurance sector still dealing with the impact of Queensland's 2011 floods and Christchurch's earthquakes, IG Markets analyst Stan Shamu said.
"Insurers have been out of favour for some time, and I think investors are really now starting to see how uncertain their earnings are, particularly with all these global events we've seen over the past couple of years or so," he said.
"These stocks have so many problems, and any opportunity or any little hiccup along the way will probably see most investors try to move elsewhere."
The insurers are likely to provide a clearer picture of the financial impact from the latest floods when they report financial results in late-February.
With the low pressure system forecast to move out to sea in the coming days, the final damage bill is unlikely to reach anything near the $2.4 billion cost of the 2011 floods.
Meanwhile, all major banks are extending their support to flood-hit customers, offering changes to loan repayments and other financial measures for home and business owners.