Unpredictability and uncertainty about future evolutions of both the system and its environment may easily compromise the behaviour of the system. The subsequent software failures can have serious consequences. When dealing with open environments, run-time monitoring is one of the most promising techniques to detect software failures. Several monitoring approaches have been proposed in the last years; however, they suffer from two main limitations. First, they provide limited information to be exploited at run-time for early detecting and managing situations that most probably will lead to failures. Second, they mainly rely on logic-based specifications, which intrinsic complexity might hamper the use of these monitoring approaches in industrial contexts. In order to address these two limitations, this paper proposes a new approach, called PREDIMO (PREDIctive MOnitoring), which, starting from scenario-based specifications, automatically generates predictive monitors that taking into account the actual status and also possible evolutions of both system and environment in the near future identify risky situations thus enabling the definition of precise strategies to prevent failures. More specifically, the generated monitors evaluate the specified properties and return one of these seven values: satisfied, infinitely controllable, system finitely controllable, system urgently controllable, environment finitely controllable, environment urgently controllable, and violated. The scenario-based notation of PREDIMO is based on the property sequence charts language that facilitates the non trivial and error prone task of specifying, correctly and without expertise in temporal logic, temporal properties. The correctness of the translation process from the properties specification to the monitors is formally proven (see the Appendix). The overall approach is tool supported and a large experimentation with OSGi (Open Service Gateway Initiative) applications demonstrates its feasibility and usability.