Understanding water temperature dynamics in lakes is essential for ecological and environmental management. This study focuses on Lake Erken, Sweden, aiming to develop and validate a three-dimensional (3D) hydrodynamic model using the MIKE 3 FM modelling system to simulate the lake's water temperature distribution. The model performance was evaluated by comparing simulated water temperature profiles with observed data at various depths, distinguishing between the upper layer and deeper layers. Results showed satisfactory performance, with the model capturing seasonal and spatial variations in the lake’s thermal structure. The root-mean-square error (RMSE) for water temperature simulation ranged between 0.7-1.8°C, and the Nash-Sutcliffe efficiency (NSE) was between 0.86-0.99 across different depths. However, the model has limitations in accurately capturing stratification in deeper layers, especially during the summer months. This research underscores the importance of accurate temperature modelling for understanding lake ecosystems and provides insights for future improvements in hydrodynamic simulations.