Surface Acoustic Waves (SAW) sensors have received an increasing interest as they reveal capable to be interrogated wirelessly without on-board power supply. Their used as stress sensor allows for remarkable linearity and repeatability. SAW devices can particularly be implemented for in-plane-stress measurement, yielding temperature compensated highly sensitive and linear sensors specially when built on AT-cut quartz wafers. However, their stress sensitivity is affected by temperature and an accurate account of the thermal impact on their mechanical properties is required for designing and calibrating the sensors properly. In this paper, we propose an experimental set-up enabling one to reliably apply controlled stress conditions to quartz substrate on which SAW resonators have been built. Finally, experimental evidence of the cross relation between temperature and stress sensitivity of the resonance frequency is reported.