Objects shown in temporary exhibitions are subject to damage caused by abrupt changes in temperature, and even more so by change in the relative humidity. Under these circumstances the changes in the atmosphere are rendered particularly sudden by the heavy and irregular influx of visitors and the unusual dimensions of the rooms. This study is based on data from two hygro-thermographs operated from the 15th to the 29th of December, 1980, during the exhibition of 43 works by Kandinsky held in Rome at the Capitoline Museum (November 12, 1980-January 4 1981). The data provided by the instruments, one inside and one outside of temporary wooden structures of the exposition, illustrate three aspects of the problem: 1) the effect of wooden walls on variations in the microclimate; 2) the number of visitors and the rhythm of their arrival; And 3) the volume of exhibition space and the number of works exposed.