This talk argues that the coterminous development of financial instruments of risk management and the British imperial expansion in the Indian ocean critical shaped the very parameters of atmospheric and colonial climate knowledge. Analyzing 18th-century merchants’ papers, Lloyd’s records, navigational journals and insurance cases fought in the marine courts in India and the admiralty courts in London shows that tropical cyclones, instead of becoming limits to be overcome simply through scientific forecasting, were instead financialized and made profitable through a brisk and thriving trade in speculative underwriting. Bridging economic and environmental history, the talk documents how the modalities and frameworks for producing knowledge about climate emanated out of the very webs of insurance and trade that enveloped the globe during this period.