High demands are placed on the material model when simulating engine components consisting of age-hardening materials that are subject to thermal-mechanical stresses and have a uniform temperature distribution. A model that takes into account the effects of aging on the material characteristics over the whole temperature profile is needed to simulate such load cases. An enhanced physical-based ageing model that takes into consideration various ageing and test temperatures is presented in this study. Under uniaxial strain-controlled isothermal loading conditions and temperatures ranging from room temperature up to 250°C, the improved model was fitted to data from the Al-Si-Mg-Cu alloy. Contrary to the previous models, this model represents much better accuracy at temperatures higher than 200°C. This updated model can be used to simulate thermomechanical fatigue testing on a cycle-by-cycle basis.