ABSTRACTIn this study, 24 climatic variables which measure various aspects of the physical controls and features of climate were subjected to factor analysis for the purpose of identifying the underlying structure of the regional climatology of Nigeria. The result of the analysis showed that 3 factors can be used to characterize the regional climatology of the country namely; the airmass residential time, the wind regime and precipitation characteristics (mainly in terms of total amount, mean intensity and length of the rainy season). These 3 factors altogether explain 91.9% of the total variation. By means of group analysis programme the country was then divided into 7 and 14 climatic regions, the first for a broad climatological study and the latter for use if detailed local work in regional climatology of Nigeria is desired.