Grounding systems in wind turbines are critical for lightning protection and managing GPR. This study investigates the influence of different soil models (uniform, two-layer, and three-layer) on GPR across six distinct geographical regions: desert, forest, agricultural, mountainous, coastal, and frozen. Simulations were performed using the CDEGS software on a standard grounding system comprising a ring electrode, horizontal electrodes, and vertical electrodes. The results reveal a strong dependence of GPR on soil characteristics and regional conditions. In desert regions, the high resistivity of dry soil significantly increases GPR, whereas in coastal areas, water-saturated layers markedly reduce GPR. In frozen regions, surface layer freezing substantially elevates GPR despite lower resistivity in deeper layers. The study demonstrates that increasing the complexity of the soil model (i.e., the number of layers) does not necessarily mitigate GPR, underscoring the need for region-specific data in grounding system design. Numerical results show the largest peak GPR for the uniform model in the frozen region during winter (≈2,197,587 V), reduced to 802,833.2 V with the three-layer model (≈63.5% reduction). Overall, in high-resistivity regions (desert, mountainous, frozen) multilayer models yield substantial GPR reductions, whereas in coastal areas changes in soil model cause only minor decreases (≈13.5%). These findings highlight the importance of tailoring grounding system designs to geographical conditions, potentially enhancing the safety and efficiency of wind turbines against lightning strikes.