An optical fiber sensing system according to the present disclosure includes an optical fiber, an interrogator connected to the optical fiber, and a vibration device disposed in a vicinity of the optical fiber. The vibration device acquires weather information regarding an installation location of the vibration device, and applies vibration according to the acquired weather information to the optical fiber. The interrogator detects vibration applied to the optical fiber by the vibration device, based on an optical signal received from the optical fiber, and determines weather conditions at the installation location of the vibration device, based on the detected vibration.