Tropical cyclones killed hundreds and caused billions of dollars in losses across Asia during July, according to research by Aon Benfield.

Impact Forecasting, Aon’s catastrophe model development centre, found the most prolific storm, Typhoon Nock-ten, killed more than 70 people and caused losses of at least $US113 million ($108.7 million) after hitting the Philippines, China and Vietnam.

Typhoon Ma-on made a brief landfall on Japan's Shikoku Island, killing five people and causing losses of around $US50 million ($48 million), while hundreds of millions of dollars in losses are expected from flooding and landslides in South Korea.

Heavy rainfall and thunderstorms across 20 provinces of China killed at least 122 and the Ministry of Civil Affairs put losses at $US1.73 billion ($1.66 billion).

Impact Forecasting President Steve Jakubowski says tropical cyclones are expected in July and the level of losses “will probably be in line with reinsurers' expectations”.

He notes the US endured at least four periods of severe weather in the month, and insured losses are estimated at $US900 million ($866 million).