Wildfires and thunderstorms in the US made the first half one of the worst on record for natural disaster insurance losses, according to Swiss Re.

The California fires alone accounted for $US40 billion ($61 billion) of the $US80 billion ($123 billion) global catastrophe insured loss, which was up 95% on the 10-year average and 29% on the first half of 2024.

Swiss Re warns losses for the year are likely to exceed its projection of $US150 billion ($230 billion), given natural catastrophe costs are usually higher in the second half.

“Losses from wildfires have risen sharply over the past decade as rising temperatures, more frequent droughts and changing rainfall patterns converge with suburban sprawl and high-value asset concentration,” the reinsurer said.

Wildfire losses comprised about 1% of natural catastrophe claims before 2015, but the figure has risen to 7% and Swiss Re says in the US, particularly California, there has been expansion into hazardous regions.

“The strongest lever to increase the resilience and safety of communities is to double down on mitigation and adaptation,” Swiss Re chief economist Jerome Haegeli said.

The US recorded $US31 billion ($44 billion) of severe thunderstorm insured losses in the first half.

Overall insured losses for the period totalled $US87 billion ($133 billion), up 85% on a year earlier.