Rio Tinto’s flagship iron ore division has made its weakest start to a year in a decade on the back of wild weather that will cost $150 million to mitigate, while its biggest Pilbara rivals appear to have escaped largely unscathed.

Rio said it would have to spend the money repairing infrastructure and hiring contractors, with the company exporting just 70.7 million tonnes of Australian iron ore in the three months to March.