Tropospheric ducts are an abnormal condition of the atmosphere that affects the propagation of electromagnetic waves, which has a direct impact on the performance of various radio systems, including mobile telephony, which is especially sensitive to these interferences in communications. Knowing what type of meteorological situations help the formation of this phenomenon allows alerting and taking measures in time, which helps to correctly manage the cuban telecommunications system. Products such as the ERA5 reanalysis are an important tool for studying tropospheric ducts as they provide high spatial and temporal resolution historical data, as well as global coverage of weather conditions. These data include three-dimensional information of temperature, humidity, and atmospheric pressure, which makes it possible to identify patterns and trends in the formation of refractive anomalies in different regions and times. Taking the study period 1981-2022, it was found that during the rainy season (May to October), surface ducts predominate, while during the dry season (November to April), elevated ducts are more common. The reanalysis data made it possible to verify that the presence of stable atmospheric conditions and the combination of a humid layer at low levels followed by a dry layer at altitude favors the formation of this type of phenomenon. This synoptic configuration mainly occurs when the Subtropical anticyclone of the Atlantic interacts with migratory anticyclones during the quarter of March - May and also interacts with tropical East waves in July. These are the periods of the year in which the most significant events occur, and the periods in which they also tend to present the greatest thickness of the duct layers, mainly in the seas to the north of the Cuban archipelago.