The purpose of this research was to obtain the rainfall forecasting model, by forecasting the monthly rainfall in Buriram province. January 2010 to December 2019 of 120 value were used and divided into 2 sets. The first 108 values from January 2010 until December 2018 were used for the modeling by Decomposition Method, Simple Exponential Smoothing Method, and Transfer Function Method. The last 12 values from January to December 2019 were used for checking the accuracy of the forecasting models via the determination of Mean Absolute Percentage Error. The research results find that the for all the forecasting methods the had been studied, Transfer Function Method is the most suitable for this time series.