An experimental study was made of heat transfer by natural convection inside packed vertical cylinders whose wall temperatures varied sinusoidally with time. The packings were small glass or plastic spheres with water as the interstitial fluid. The purpose of this research was to stimulate, in a controlled laboratory model, the heat transfer to grain stored in bins. Temperature distributions throughout the bed were determined for various sizes of packing, several height‐to‐diameter ratios, and for a number of frequencies of sinusoidal forcings. The results are presented graphically in terms of the amplitude ratios of the interior temperatures to the wall temperature and the phase lag between the interior and wall temperatures. The operating conditions ranged from essentially pure conduction to moderately strong natural convection. The temperature distributions near the wall of the cylindrical container were found to be predicted by a simple one‐dimensional model. Temperature distributions throughout an entire packed bed were quite complex when there was significant natural convection and, although general overall predictions were possible, accurate calculation of the temperature at a specific location and time was impossible.