Khasana, Kartika Nur2022-07-212022-07-212022-01PerpustakaanElfitrahttps://repository.unri.ac.id/handle/123456789/10576Indonesia is a country with a tropical climate so the region has a fairly high rainfall. In this study, predictions of the rainfall period for Pekanbaru City were made from 2016-2020. This study uses the Fast Fourier Transform method with the data used is monthly rainfall data with a time span of 2016-2020. The result of the FFT program is a graph that relates the month, frequency, and period to the rainfall and the rainfall function to the month. The graphs obtained are 4 frequencies, namely 0.016949 cycles/month, 0.050847 cycles/month, 0.084746 cycles/month, and 0.169492 cycles/month, which correspond to the 4 periods obtained, namely 5.90, 11.80, 19.67, 59.00. The results of this study indicate that the highest rainfall occurred in November 2016 in the 2016-2020 periodenRainfallFast Fourier TransformPeriodArticle