In order to better understand and predict the intragrain heterogeneous deformation in a 6063 aluminum alloy deformed at an elevated temperature, when additional slip systems beyond the usual octahedral slip systems are active, a modeling framework for analyzing representative polycrystals under these conditions is presented. A model polycrystal that has a similar microstructure to that observed in the material under consideration is modeled with a finite element analysis. A large number of elements per grain (more than 1000) are used to capture well the intragranular heterogeneous response. The polycrystal model is analyzed with three different sets of initial orientations. A compression test is used to calibrate the material model, and a macroscale simulation of the compression test is used to define the deformation history applied to the model polycrystal. In order to reduce boundary condition effects, periodic boundary conditions are applied to the model polycrystal. To investigate the effect of additional slip systems expected to be active at elevated temperatures, the results considering only the 12 {111}⟨110⟩ slip systems are compared to the results with the additional 12 {110}⟨110⟩ and {001}⟨110⟩ slip systems available (i.e., 24 available slip systems). The resulting predicted grain structure and texture are compared to the experimentally observed grain structure and texture in the 6063 aluminum alloy compression sample as well as to the available data in the literature, and the intragranular misorientations are studied.