The North American Monsoon system, although smaller in size and magnitude than its Asian counterpart, is an important feature of summertime climate over the southwestern United States and Mexico. Differential heating between land and ocean is the basic mechanism which drives monsoon circulations. A goal of this study is to examine the components of differential heating characterizing the North American monsoon and determine the relative importance of the processes of convection, radiative forcing, and air-sea interaction. The monsoon activity, which begins in June and continues into September, exhibits considerable variability on daily, weekly, and monthly time scales. Understanding the monthly evolution of differential heating over the summer monsoon season is of considerable interest and this study will illustrate the relationship between the differential heating and the circulation features. Also, a well known, salient feature of the North American monsoon is the diurnal change in convection and rainfall. Using high resolution model simulations from the Florida State University Global Spectral model, this study examines the diurnal variability in the components of differential heating and the related response of the motion field.