The values of the atmospheric refraction index N for ultra-short radio waves for the territory of Buryatia according to the data of meteorological stations were calculated. The monthly average values N contours maps for the central months of the seasons of 2020 were constructed. It is shown the humidity of Lake Baikal and the relief significantly influence N. On average, the values of the refractive index near the lake are 20–30 N-units higher. It is revealed the monthly average N values have maxima in winter and summer with minimums in spring and autumn, with the main maximum occurring in July.