Abstract: Rainfall seasonality in Nigeria is expected to be subjected to some alteration due to climate change, with some adverse consequences for water resources and the agro-hydrological system. Due to the dearth of knowledge about future changes in rainfall regime, this study analysed the relative seasonality of rainfall for the historical (1971-2000) and late-century (2071-2100) periods over the Hadejia-Jama’are River Basin using Walsh and Lawler’s rainfall seasonality index. The trends in the time series of the seasonality indices were examined using the Mann-Kendall trend test. The rainfall seasonality index showed that the rainfall regime during the late century will remain generally seasonal, similar to the regime for the historical period, with indices in the range of 0.60 to 0.79. The Mann-Kendall trend test indicated no significant changes in the rainfall regime of the study period. The results indicate among others, that there are likely to be minimal changes in local convective activities during the late-century.
Key words: Climate model, Future rainfall, Northern Nigeria, River, Seasonality index