Nowadays, global climate change makes urban planners and designers pay more attention to thermal islands to enhance thermal comfort conditions in cities. The present study aims to investigate the effects of evergreen and deciduous tree placement patterns, tree canopy height, and tree canopy diameter on the enhancement of ambient temperature and improvement of thermal comfort conditions. The ENVI-met model was used to replicate the research region and site. It was validated by comparing the outputs of the model with the values from field measurements. Finally, the recommended scenarios were simulated in the model to discover those scenarios with better performance in enhancing outdoor thermal comfort and temperature on days with low temperatures. At low-temperature situations, planting evergreen trees irregularly had a stronger impact on the improvement of thermal comfort (PMV) compared to deciduous trees. Furthermore, in all models, Populus nigra and Platanus showed the worst performance in boosting ambient temperature. Landscape designers and urban planners might use the findings to improve urban green space, construct sustainable cities, and enhance air temperature.