In this paper, we propose a new calculation method for evaluating the inhomogeneous outdoor thermal environment by incorporating a multi-node human thermoregulation model into the simulation method based on CFD analysis of the outdoor thermal environment. We also investigated the effects of weather conditions on the inhomogeneity of the radiant environment and the thermal comfort for pedestrians using the proposed calculation method. Two different weather condition cases are investigated in this study: (1) a scorching hot day and (2) a cloudy day. The multi-node thermoregulation model “JOS” is used in this analysis to investigate the inhomogeneity of the outdoor thermal environment. The analysis confirmed the effectiveness of the proposed method in the evaluation of the inhomogeneity of the thermal comfort in outdoor space.