Predictions are carried out for radiation heat flux incident on a base surface from a gaseous conical plume with radial and axial temperature variations. A forward Monte Carlo method is developed and validated by comparing the results of an isothermal cylindrical plume, a conical plume with axial temperature variations, and a cylindrical gas-filled space. The minimum number of random emission sites in the plume required to obtain reasonable estimates of heat flux is determined The radial temperature variations in the plume are shown to result in significant reduction in heat flux. The method assumes the plume to be gray and therefore the spectral dependence of plume properties is not considered.