Tourism is vital to national economies and income of its individual citizens. This paper investigated the suitability of climate for tourism in Northwestern Nigeria using the tourism climate index developed by Mieczkowski (1985). Parameters used for calculating the index include monthly average maximum daily temperature, rainfall, mean daily relative humidity, minimum relative humidity, total wind speed and sunshine hours. The stations used for the calculation of TC index include Kaduna, Kano, Katsina and Sokoto. The result is presented in the form of charts using excel, while GIS is used for zoning of tourism climatic conditions in different months. Result shows that the study area is suitable for tourism throughout the year, as all the TCI scores ranges from 94 to 41 (‘ideal’to ‘marginal') except for Kano in the month of June which has a TCI score of 39 (‘unfavorable’). The months of January, February, November and December are the best months for tourism as they recorded higher TCI values of 73 to 94 (‘very good’to ‘ideal’). It is therefore concluded that the best time for tourist to visit Northwestern Nigeria is during the months of January, February, November and December.