Risk Management Solutions (RMS) estimates Hurricane Isaac caused insured losses of $US1 billion to $US2 billion ($954 million to $1.91 billion).

RMS Model Product Management Director Christine Ziehmann says the range reflects uncertainties around losses at low wind speeds when Isaac was at tropical storm strength, plus leakage of surge-related losses into wind-only loss payments.

The risk modeller says there have been 14 tropical storms in this year’s Atlantic hurricane season, with seven strengthening to hurricanes. The number of storms will exceed forecasts for the season made last month.

Although it is the second most active season for named storms since records began in 1851, only one, Michael, has been a major hurricane.