This work is a numerical analysis of the thermal effect on the elastohydrodynamic behavior of elastomer radial lip seals. Two thermal approaches are considered, a local approach that determines the distribution of temperature in the contact zone and a simplified global approach that considers a mean temperature of fluid film. In addition, the thermoelastic behavior of the lip surface is taken into account with a relationship between Young’s modulus and the mean temperature of the lip surface. It is shown that the local temperature of the contact zone increases sensitively according to the shaft speed. Moreover, all operating characteristics such as film thickness and power loss are significantly influenced by the local temperature effect.