The Asian monsoon season caused nearly $US7 billion ($7.1 billion) of damage last month, according to Aon Benfield’s catastrophe report for September.

The worst-hit area was China, with flooding and landslides causing $US4.25 billion ($4.3 billion) of damage and killing more than 100 people.

In Thailand the August floods continued into September, with the damage bill estimated at $US1.1 billion ($1.12 billion) and 1.13 million homes damaged.

Aon President of Impact Forecasting Steve Jakubowski says the heavy rainfall has affected a much wider area of Asia than usual this year.

“In many areas, reinsurance penetration remains relatively low,” he said.

“Flood modelling is still a science in progress and in these Asian regions, scientific communities are striving to understand the peril and its effects so governments can best mitigate the seasonal rainfall.”

Mr Jakubowski says once this is understood, the reinsurance industry can structure and price products to assist in the management of the risks.

Apart from the monsoon season, Asia was also hit by a number of tropical cyclones last month.

Typhoon Nesat hit the Philippines, China and Vietnam causing damage worth $US1.39 billion ($1.42 billion), while cyclones Roke and Talas struck Japan leaving a damage bill of more than $US300 million ($306 million).

In the US, Tropical Storm Lee landed in Louisiana before shifting northwards leaving more than 80,000 claims and payouts exceeding $1 billion ($1.02 billion).

In the UK, the remnants of Hurricane Katia brought high winds and heavy rain. As a result, the Association of British Insurers put the damage and clean-up bill at more than $US158 million ($161 million).

Away from hurricanes and storms, central Texas faced wildfires during the month that destroyed at least 1554 homes and payouts have already exceeded $US500 million ($510 million).