Abstract: A method and apparatus for the controlled aeration of stored grain is disclosed that provides for aeration of grain when ambient temperature and relative humidity levels are within a specified range of optimum levels. Available daily aeration time is selected by the operator and, if not used on a given day, is accumulated. Aeration of grain is initiated when the current ambient air temperature is within an acceptable range of the recent average air temperature, the equilibrium moisture content supported by the current air temperature and relative humidity levels is within an acceptable range of the desired grain moisture content and the available aeration time has not been used up. Long periods between aeration are avoided by progressively widening the range of acceptable current ambient air temperature and equilibrium moisture content levels when less than a predetermined amount of aeration has occurred.