Insurers sustained losses of $US3.3 billion ($4.83 billion) from thunderstorms with tornadoes in midwestern parts of the US in May – the industry’s most costly natural disaster in the first half of the year, Munich Re says.

The insured portion of the May US storms came to around $US2.5 billion ($3.66 billion).

Total first-half insured losses declined to $US15 billion ($21.94 billion) from $US17 billion ($24.86 billion) in the corresponding period last year.

Overall losses of $US42 billion ($61.43 billion) were up from $US33 billion ($48.27 billion) a year ago and compared with a 30-year average of $US69 billion ($100.92 billion), inflation adjusted.

The latest figure does not include losses from severe floods in southeast China, which began in June and reportedly caused billions of dollars in damage.

Asia-Pacific region losses totalled $US16 billion ($23.4 billion), around half the long-term average. The costliest disaster for insurers in this region was the severe flooding in Queensland which produced overall losses of almost $US2 billion ($2.93 billion), of which just under half was insured, Munich Re says.