California was scorched by wildfires last month, with insured losses passing the $US1 billion ($1.39 billion) mark, according to the latest catastrophe report from Aon Benfield subsidiary Impact Forecasting.

The Valley Fire, northwest of San Francisco, was the third-most damaging blaze in state history, killing four people and destroying nearly 2000 buildings.

Preliminary insured losses were estimated at more than $US925 million ($1.28 billion).

The Butte Fire, southeast of Sacramento, killed two people and resulted in insured losses of at least $US225 million ($312.39 million).

Head of Impact Forecasting Adam Podlaha says it is already the costliest year since 2007, and the California wildfire season is just beginning to peak.

“The severity of the September wildfires in California serves as a reminder of how costly the peril can be for the insurance industry,” he said.

Officials in Indonesia say this year is their worst for wildfires since 1997, following $US4 billion ($5.55 billion) in economic losses from blazes in Sumatra and Kalimantan.

Also last month an 8.3-magnitude earthquake hit central Chile, killing 16 people and prompting evacuation of more than 1 million. Economic losses were close to $US1 billion ($1.39 billion).

Japan suffered extensive flooding, killing eight people and destroying 20,000 homes, with insurers estimating payouts of at least $US250 million ($347.1 million).

Typhoon Dujuan struck Taiwan and China, leaving three dead and hundreds injured. Economic losses reached $US680 million ($944.12 million) and insured losses $US79 million ($109.68 million).