Comparative analysis of the monthly values of Tourism Climate Index (TCI) in the South Caucasus countries capitals (Baku, Tbilisi, Yerevan) are presented. The statistical structure of TCI is studied. In the indicated cities between the TCI values are the high linear correlation, which reaches 1. The intra-annual distribution of the TCI values for all cities has bimodal nature with the extremum during June and September and by the polynomial of the ninth power are described. In Tbilisi, in comparison with Baku and Yerevan, from May through September somewhat decreased values of TCI are observed, which is caused by heavier precipitation and smaller sunshine duration in the capital of Georgia. As a whole, the climate of all three capitals is suitable for the year-round mass tourism (TCI categories changes from “Marginal” to “Excellent” in Tbilisi and from “Marginal” to “Ideal” in Baku and Yerevan, with the average annual category for all cities–“Good”).