The predominant method of sheet metal welding, is undoubtedly resistance pressure welding. It is considered the most economically viable joining technique, due to its high operation speed and automatability. Therefore, it is highly valued in manufacturing of e.g. automotive industry or battery production lines. The technique is very mature, yet has been intriguing researchers for many years, owing to the mechanical, thermal, electrical, electromagnetic and metallurgical phenomena occurring simultaneously throughout the process. Establishing a numerical model of such a highly dynamic and multi-physically complex process enhances the understanding of the mechanisms that support weld formation and the fracture mechanics of welds. Moreover, it enables industry to predict weld formation a priori and to select welding parameters resulting in a good weld quality. For this purpose, it is of utmost importance to have a model which is capable of representing the physical process as accurately as possible and this makes validation of these numerical models an essential step prior to deployment. For validation purposes, the temperature history and weld nugget geometry obtained through simulation are often compared with reality. During the process, weld nucleation and growth start at the interface of the metal plates. As such, it is not practicable to directly measure the temperature reached throughout the weld cross-section and therefore the determination of the temperature field is currently solely based on the microstructure after the process. However, not all products in industry can be destructively examined for model validation purposes in high enough numbers. This paper accordingly focuses on non-destructive validation methods for the validation of the proposed coupled finite element analysis. First, a multi-physically coupled finite element model of a resistance spot welding process is presented. This model incorporates the electrical, mechanical and thermal phenomena involved in the welding process. Subsequently, a novel validation strategy is presented based on experimental welding measurements. This work contains both simulation and measurement data from experiments based on varying welding parameter sets and focuses in particular on the use of both on-line temperature measurements and ultrasonic tests performed respectively during and after the welding process. Finally, the weld geometry and temperature field stemming from numerical simulations are validated and the results are compared with current destructive validation techniques.