A weakly nonlinear analysis of the Go¨rtler vortex problem is performed. It is demonstrated that the system of streamwise vortices enhances the heat transfer rate at the wall. The inherently nonlinear physical mechanism responsible for this enhancement is discussed both mathematically, as well as heuristically; the latter using kinematic arguments. Remarks are made on the relation of the weakly nonlinear results to their fully nonlinear counterparts, as well as on the inadequacy of linear analyses.