Purpose of the work: to consider the concept and essence of seasonal fluctuations in the series of dynamics, to determine the methods of study and features of trends in the development of series of dynamics. The topic of this work is relevant, because seasonal fluctuations usually negatively affect the results of production activities, causing disruptions in the rhythm of production. Therefore, economic organizations are taking measures to mitigate seasonality through a rational combination of industries, mechanization of labor-intensive processes, and the creation of agro-industrial firms