The insured losses from the severe thunderstorm outbreak that struck US from May 20-27 are expected to cause between $4bn and $7bn, according to the catastrophe modeling firm AIR Worldwide.

AIR said the losses include residential, commercial, and industrial properties and their contents, and to automobiles, while non-modeled losses, including loss adjustment expenses, were excluded.

Kansas, Minnesota, Texas, Indiana and Missouri states were hit hardest by the severe weather in late May.

AIR added that the city of Joplinm, Missouri, saw the massive tornado named as EF5, on May 22, which was termed as the deadliest tornado to hit the US in more than half a century.

AIR Worldwide principal scientist Tim Doggett said the severe weather funneled across a corridor that stretched from Lake Superior to central Texas and east through Missouri, Tennessee, Kentucky, Ohio, and to the East Coast, impacting more than 20 states in all.

"It is also becoming quickly apparent that 2011 will surpass 2008 in terms of insured losses from severe thunderstorm activity. Indeed, the two major outbreaks of this year — the first in late April, the second in late May — are the costliest on record," Doggett said.