In this study, the interaction between a tridimensional flow field and an urban street canyon, has been analyzed. Considering different ambient wind velocity intensities and directions, several numerical simulations have been performed. The aim of this study is to investigate the effect of solar radiation, within a street canyon, for various characteristics of the ambient flow field. In the first part, the buoyancy effects have been excluded and the impact of tridimensional effects on the flow field has been evaluated. In the second part, the natural convection effects on the flow structures and the heat processes have been analyzed. Through the evaluation of the Richardson number an analysis of the convective heat transfer coefficient has been performed. The results show the importance of considering a tridimensional model and the impact of the longitudinal velocity component on the heat transfer processes along the street canyon. (C) 2014 Elsevier Ltd. All rights reserved.