A method of measuring weld thermal response as a function of time during the production of a resistance weld includes monitoring a first parameter responsive to a change in an electrode mechanical load on workpieces welded together with respect to the electrode mechanical load applied prior to application of the heat, monitoring a second parameter responsive to a change in position of linkage applying the electrode load with respect to linkage position prior to application of the heat, and processing a composite of the first parameter and the second parameter to produce a derived measurement representative of the thermal response of the weld. Electrode force and electrode current are also monitored via sensors and measurements calibrated to provide more accurate information during the welding process.