Abstract <p>The problem of developing effective methods for predicting the defining characteristics of polymer composites under the influence of extreme environmental factors characteristic of the climatic conditions of the Arctic and Subarctic zones has been investigated. The formulated problems of developing effective forecasting methods are investigated within the framework of refined variational formulations based on modern provisions of the kinetic theory of strength. A number of fundamental principles and concepts were introduced that make it possible to optimally coordinate the defining parameters calculated on the basis of the constructed mathematical models at the macro level with the defining parameters of physical models describing molecular interactions at the micro level. A methodology has been developed for matching the parameters of mathematical and physical models at the micro and macro levels, which made it possible to solve the problem of restoring the parameters of physico-chemical processes occurring at the micro level, leading to destructive changes in composites and deterioration of their characteristics over time. Based on the conducted physical experiments, an objective assessment of the parameters of destructive chemical reactions in composites was carried out, which made it possible to construct effective generalized models of durability for a long-term period, as well as to conduct a constructive analysis of the influence of individual extreme factors on durability. The results of computational experiments are presented.</p>