This research studied the quantitative modeling of rainfall amount for different eco-climatic regions of Nigeria.The key parameters of the model developed were Cold Cloud Duration and rainfall producing mechanisms.CCD data and rainfall data from existing gauging stations in the different eco-climatic regions of Nigeria for 10 years (1996-2005) were used for this study. Consequently step-wise multiple regression models were run at two levels. The first level had CCD, ITD, DL, and P as the major independent variables; while the second level included CNT in the models. The result of the first hypothesis showed that the CCD alone was not adequate to determine the amount of rainfall in different eco-climatic regions of Nigeria. The combination of CCD and ITD was found to account for greater variability of rainfall amount in the country. The result of the second hypothesis showed that the inclusion of CNT in the modeling did not yield a better result. The study showed clearly that the model involving the CCD at -40 degees Celsius and the ITD was the most appropriate for modelling rainfall amount in Nigeria.