The frequency of rainstorms has been increasing with climate change. Rainstorms are extreme weather events that can severely impact people’s lives, property, and socioeconomic development. Vulnerability as it relates to climate change has been widely discussed. The Third Assessment Report of the Intergovernmental Panel on Climate Change proposed an Exposure-Sensitivity-Adaptive capacity (ESA) framework for vulnerability assessment. Flood disaster vulnerability based on the ESA framework has been studied, while few studies have focused on rainstorm disaster vulnerability. In this study, Liaoning Province of China is selected as the study area. A rainstorm disaster vulnerability index system is created based on the ESA framework, and precipitation and economic and social development are used. Random Forests is used to analyze the spatial-temporal characteristics and feature importance. The results show that grade variation is decreasing, but grades are still high. Grade variation shows an “increase-decrease-increase” pattern from West to East. Grades are closely related to hazard-sensitive population, economic development levels, people’s income, and agriculture infrastructure levels, economic and social development indicators are the key to disaster prevention and mitigation. Our study not only contributes to enriching the research on rainstorm disaster vulnerability, but also offers new ideas for the improvement of disaster prevention, mitigation capacities, and policy formulation.