We present the application of a portable radial in-plane speckle interferometer to the measurement of residual stresses when local heating is used as a stress relaxation technique. We also present a numerical method to calculate the residual stresses from the radial in-plane displacement field that is measured subsequent to the heating and cooling of the interrogated spot. A finite element analysis of the thermomechanical response of the specimen under test is performed to adjust the model used for residual stress determination. To evaluate the performance of this technique, results obtained using several preloaded specimens are compared with the stress introduced in them. It is shown that the speckle interferometer and local heating combined system allows the measurement of residual stresses with an average deviation of approximately 7% for a range of uniaxial stresses from 25 up to 75% of the yield stress of the material.