Combined forced and natural convection from a rotating horizontal heated cylinder placed in a low-speed wind tunnel is investigated through numerous experimental set in the counterflow arrangement, i. e. , with the free-stream velocity directed parallel to the gravity vector and opposite to the natural convection flow. The main goal of this work was to determine the dependence of the overall heat flux from the rotating cylinder, represented by the Nusselt number, on the free-stream Reynolds number, the rotational Reynolds number, and the Rayleigh number. Several correlations documenting this dependence were obtained and are presented in this paper.