The aim of the paper is to examine combined free and forced convection in open isothermal cubic cavity. The experimental apparatus, enabling convective heat transfer coefficient, was particularly designed for this study. Three cavity models were built and tested, varying the surface temperature, the external wind velocity, the angle of incidence and the angle of attack. As a result, a correlation among Nuselt, Grasshof and Reynolds numbers was obtained with high certainty. Using simple visualization technique, fluid field structure is analyzed for different positions and angles of attack of the external flow. In order to study interaction, results obtained by visualization are compared with maps of surface distribution of the local heat transfer coefficient. Conclusions performed enable control of the convective heat transfer process in the cavity, what is important for application in the technical practice.