Rainfall is the most important weather element that played critical role in human life. Located in tropical region, Indonesia has great variability of rainfall that influenced by various factors including global, regional, and local scale phenomena. To achieve better rainfall prediction accuracy, we have to understand factors that contribute to rainfall formation process. In this study, we conducted spectral analysis of rainfall in Tanjung Priok. As the busiest port in the country, there was a demand of high precision weather forecast in Tanjung Priok region. Spectral analysis was used to recognize rainfall pattern in the location. The result showed that rainfall in Tanjung Priok followed the annual cycle, while rainfall anomalies observed six periods of 19 dasarians, 31 dasarians, 3 dasarians, 42 dasarians, 114 dasarians, and 228 dasarians. These periods were indicated as the period of ITCZ, Madden-Jullian Oscillation, dipole mode, and El Nino / La Nina.