Precise and detailed knowledge of the dynamic characteristics of structures has become increasingly important in recent years. As a consequence, the accuracy of experimental data, which is often used to validate and to update finite element models, has become extremely important. It has been shown experimentally that small changes in ambient temperature can cause distinct variations in the natural frequencies of a lightly damped structure which, in turn, may result in significant errors in experimental and analytical results. Therefore, a good understanding of the physical driving mechanisms involved is necessary so that adequate stability control measures may be implemented. This paper presents an analytical investigation of the variations in natural frequency caused by small changes in temperature. An analytical plate dynamic model is developed accounting for the effects of temperature- dependent material properties. Changes in temperature influence Young's modulus, structural dimensions (via thermal expansion), and boundary condition effects. These change cause variations in the natural frequencies which result in marked changes in structural dynamic response at frequencies near resonance, especially when damping is low. Natural frequencies decrease linearly with increasing temperature over the limited temperature range in this study. A sensitivity analysis indicates that the temperature-dependence of Young's modulus is the dominant factor influencing the variations in natural frequency, but boundary condition effects may also be important.