The outphasing amplifier has alternative linearity requirements when compared with traditional amplifier technology. As a relatively new architecture for mobile communications the physical and electrical causes of nonlinearity have not yet been fully identified. In this work the effect of thermal variations on the characteristic operation of the outphasing amplifier architecture is investigated. More specifically the impact that gain and phase variations which result from a change in device temperature affect the characteristic performance of the outphasing amplifier. Amplifier biasing circuits commonly account for changes in temperature, a process which will result in a shift in characteristic performance. The result demonstrates a shift in characteristic outphasing angle of as much as 2.4 degrees and a reduction in dynamic range greater than 20 dB.