Travel and Tourism as a sector has been resilient despite the diverse climatic conditions that affect tourists. Climatic conditions prevailing in the tourist destinations determine the number of tourists visiting those destinations. In 1985, Mieczkowski developed the Tourism Climate Index (TCI) to estimate the impact of climatic conditions on tourism. A mathematical model for Tourism Climate Index South African (TCISA) is proposed. Five climatic variables such as maximum temperature, minimum temperature, precipitation, cloud cover and wind speed are used as the input to the index to estimate the values of TCISA. The model for TCISA is validated using the climate data for the Durban region. Results show Durban as one of the popular tourist destinations due to its climate suitability for various tourist activities. This is comparable with the data from TripAdvisor. This study recommends the validation of the mathematical model by using more data points and climatic variables.