Boltzmann generators approach the sampling problem in many-body physics by combining a normalizing flow and a statistical reweighting method to generate samples of a physical system's equilibrium density. The equilibrium distribution is usually defined by an energy function and a thermodynamic state, such as a given temperature. Here we propose temperature-steerable flows (TSF) which are able to generate a family of probability densities parametrized by a choosable temperature parameter. TSFs can be embedded in a generalized ensemble sampling framework such as parallel tempering in order to sample a physical system across thermodynamic states, such as multiple temperatures.