Rainfall erosivity considers the rainfall amount and its intensity. This is an important parameter for soil erosion risk assessment under future land use and climate change. Comparisons of all climatic parameters show that rainfall is directly involved in the loss of soil quality during torrential rain. The effect of rainfall erosivity in Penang was considered for two stations, Air Itam and Simpang Ampat. Monthly as well as annual rainfall was obtained from the Department of Drainage and Irrigation, Malaysia for thirty years (1983-2012). Trends analysis of the rainfall data were obtained for each decade that shows trends for mean monthly rainfall. This was conducted using Mann-Kendall trend analysis and Sen's slope tests. Trend analysis shows that there is no significant difference in mean monthly rainfall for the studied period except for Simpang Ampat. The Fournier indexes were used to determine the effect of extreme rainfall events towards soil erosivity. Air Itam recorded 10% cases of very severe impact using Fournier index and 3.33% cases of very high impact using modified Fournier index. The result shows that there is a positive correlation between rainfall trends and soil erosivity.