The agency will work alongside the Met Office press team based in Exeter to promote its products and consultancy aimed at sectors including utilities, renewables, oil and gas, aviation and marine, as well as its public weather service.
The pitch process was led by Jo McLellan, head of comms planning at the Met Office.
McLellan said: "We wanted to look at new ways of extracting maximum value from our content and find new media platforms to showcase our expertise in the application of weather and climate science in the business-to-business arena.
"3 Monkeys demonstrated it grasped the potential to promote our products and services more widely and to increase our profile beyond the forecasting services that most people know us for."
Christine Jewell, 3 Monkeys MD, said: "This is an exciting time for the Met Office and we’re relishing the opportunity to help it boost business awareness of just how much it offers by tapping into an immensely rich and interesting seam of unique content. "