Rainfall variability in Lagos State, Nigeria, poses significant pluvial flood risks, particularly during the high-risk months from May to October. This study applies time series analysis using the ARIMA (2,0,1) model to forecast rainfall patterns from 1980 to 2022 and identify periods of heightened flood susceptibility. Stationarity was confirmed through the Augmented Dickey-Fuller test, and seasonal decomposition revealed consistent peaks during the rainy season.