In the Union of Soviet Socialist Republics, based on full-scale tests on experimental overhead lines, guidelines for considering corona losses and interference were developed. The aim was choosing wires for overhead power lines of alternating current for a voltage of 330-750 kV and direct current for a voltage of 800-1500 kV. Currently, the current instructions use the average values of active power losses per corona for overhead lines. This paper considers the corona loss power curves considering various climatic conditions. The determination of metrological parameters is based on the analysis of weather data and patterns of the weather types. The paper assesses the impact of electricity losses per corona using various factors on the example of the real 330 kV overhead line in the Republic of Belarus. The method based on average statistical relative air density and geometric parameters of the prevailing section of the overhead line was proposed and presented. © 2023 IEEE.