Rainfall-induced slope failure is a significant concern for geotechnical engineers. In dry conditions, many vertical slopes remain stable because matric suction or negative pore water pressure in unsaturated soils increases the effective stress, thereby enhancing shear strength compared to saturated soils. This study evaluates slope behavior under varying rainfall intensities and slope angles. A series of numerical analyses was performed using PLAXIS 2D finite element software with a fully coupled flow-deformation formulation. The Mohr–Coulomb failure criterion was employed to represent the soil’s nonlinear stress–strain behavior. To simulate rainfall-induced slope stability, the study modeled rainfall intensity over time using Van Genuchten’s Soil–Water Characteristic Curve (SWCC). Outputs such as safety factor, deformation, matric suction, and effective soil saturation were evaluated concerning input parameters, including soil shear strength and permeability. Results indicate that the slope safety factor gradually decreases with increasing rainfall intensity and recovers as rainfall subsides. Moreover, continuous heavy rainfall over one day shifted the slip surface from deep to shallow, while a transition from heavy to medium to light rainfall resulted in a deeper critical failure surface.