A rack acclimating device can accelerate the acclimation of an already assembled rack of computing equipment to an environment. A rack acclimating device can comprise one or more heating elements and an air moving device that can be oriented to move air across the heating elements and then through the rack of computing equipment. Additionally, the rack acclimating device can comprise a controller or other like computing device that can receive environmental sensor data and, based upon the received environmental sensor data, can control the heating elements and air moving device. Environmental sensor data can be received from environmental sensors, such as temperature and/or humidity sensors, which can be positioned to sense various environmental aspects. A rack acclimating device can also comprise a hood or other like structure to confine and direct the heated air from the heating elements and/or air moving device to the computer equipment rack.