A simple, two‐dimensional, spectral model of heat transport in the Venus ionosphere has been constructed. Numerical experiments with the model suggest that a nocturnal heat source about an order of magnitude smaller than the daytime source is required to simulate the observed ion and electron temperatures. The solar zenith angle dependence of the high‐altitude ion temperature appears to be caused by expansion followed by compression of the plasma as it flows from the dayside to the nightside. Thermal‐flux saturation appears to be significant on the nightside, but the formation of a standing shock wave does not seem to be required to explain the broad features of the observed, nocturnal ion temper