Claims arising from last month’s California wildfires could reach $US13 billion ($18 billion), according to various industry calculations.

Catastrophe modeller AIR Worldwide puts the combined bill from the Camp and Woolsey blazes at $US9-$US13 billion ($12.4-$18 billion), describing the former as the “deadliest and the most destructive single wildfire” in the state’s history.

Damage inspections are continuing after the Camp fire, which burned more than 62,000 hectares and destroyed at least 18,700 structures.

Impact Forecasting’s monthly recap says the two fires and other blazes will take US wildfire payouts past the $US10 billion ($13.8 billion) mark for the second year running.

The Aon-owned modeller predicts the severe storm that hit Sydney and parts of NSW last month will cost insurers at least $13.5 million.

Other notable disasters last month included a magnitude-seven quake in Alaska, which is likely to have caused economic losses of more than $US100 million ($138.3 million).

Severe weather in Italy and Spain will push overall economic losses to more than $US3.5 billion ($4.8 billion), Impact says.