Insured losses from Hurricane Irma will probably range from $US32-$US50 billion ($40-$62 billion), changed from an earlier $US20-$US65 billion ($25-$81 billion) estimate, according to catastrophe modeller AIR Worldwide.

The loss estimates cover the US and affected Caribbean islands.

Irma struck the Caribbean islands as a Category 5 storm before making another landfall on September 10 (US time), when it hammered the Florida Keys as a Category 4 storm.

It spared the east coast of Florida, including the highly urbanised areas of Miami, Fort Lauderdale and West Palm Beach, where residential and commercial properties are valued at about $US1.2 trillion ($1.5 trillion).

Initial modelling showed the storm heading towards the three urban areas.

“Had Irma struck the east coast of Florida, close to Miami… insured losses could have been much greater,” a spokesman for AIR Worldwide told insuranceNEWS.com.au.

AM Best says Irma “was weaker than expected” but still caused significant damage that will challenge the Florida insurance market.

“Even though losses will clearly not be as severe as originally thought, Irma will remain a sizeable event and will test the infrastructure and, potentially, the financial wherewithal of some writers, particularly those that are concentrated,” the ratings agency says.

“Hurricane Irma may also force insurers to rethink their risk selection/appetites and reinsurance purchases.

“The storm could prompt some concentrated companies to increase their focus and efforts on diversifying outside of Florida, while others may revamp products to more desirable coverages.”