Last week’s devastating tornadoes in the US are expected to cost insurers $US2 billion-$US5 billion ($1.8-$4.5 billion), with Eqecat warning that the tornado season has only just begun.

The catastrophe risk modeller says this is already one of the most active tornado seasons ever recorded, with the National Weather Service reporting tornado activity so far this year is about 30% higher than the historic recorded maximum.

The same extreme weather patterns causing tornadoes are leading to heavy rainfall in the US Midwest, it says.

“This run-off is leading to serious flood conditions with many roads and highways blocked, thousands of acres of agricultural land inundated, and many towns already under water.”

Eqecat says large winter snowstorms have created record flood conditions along several stretches of the Mississippi, Ohio, Illinois, James and Red rivers, as well as several smaller rivers. 

“Major flooding is expected to occur through the next week.”

In addition, strong winds in west Texas this month have fuelled bushfires there, with insured losses expected to be above $US100 million ($91 million). But Eqecat expects them to rise further because critical fire conditions are forecast.