US insurer Chubb says recent cold weather is to blame for a 16.5% plunge in first-quarter net profit.

“Results were adversely affected by catastrophe and non-catastrophe losses related to severe winter weather in the US,” President and CEO John Finnegan said.

Net profit in the three months to March 31 was $US375 million ($478.7 million), compared with $US449 million ($573 million) in the corresponding period last year. Net written premium grew to $US3.11 billion ($3.97 billion) from $US3.06 billion ($3.91 billion).

The combined operating ratio deteriorated to 93.9% from 93.2% as catastrophe losses grew to $US250 million ($319 million) from $US199 million ($254 million).