  This study investigates the trend in Rainfall Onset Dates (ROD), Rainfall
Cessation Dates (RCD), Length of Growing Seasons (LGS) and Rainfall Amount at
Onset of Rainfall (RAO) using linear regression, Mann-Kendall, Sen Slope and
Hurst Exponent for four locations in tropical Nigeria and the development of a
Fourier based model for ROD and RCD. Daily data was obtained from the Nigerian
Meteorological Agency for thirty-four (34) years (1979 - 2013). ROD and RCD
were computed using the method of cumulative percentage mean rainfall values.
Maiduguri, Gusau and Ikom showed positive trends in ROD and RCD while Ibadan
exhibited negative trends in the two parameters. Anti-persistence was observed
in ROD, RCD and LGS for three locations (Maiduguri, Gusau and Ibadan). A
Fourier based model with seven (7) coefficients was developed to model ROD and
RCD for all the locations. The model developed performed very well in all
locations with the best performance obtained in Gusau and Ibadan for ROD and
RCD respectively. The effects of climate change on agricultural output for the
four (4) locations under consideration were highlighted and adaption techniques
suggested for mitigating the impact on agricultural output and livelihood of
citizens in the areas.
