Stretchable electronics and sensors have been attracting significant attention due to their unique characteristics and wide applications. This paper demonstrates a prototype of a fully stretchable temperature sensor on an elastomeric substrate. The sensor was first fabricated on a silicon-on-insulator (SOI) wafer and then transferred to a pre-strained elastomeric polydimethylsiloxane (PDMS) substrate. Releasing the pre-strain on the PDMS substrate led to the formation of the microscale, periodic, wavy geometries of the sensor. The thin wavy sensor device can be reversibly bent and stretched up to 30% strain without any damage or performance degradation. A theoretical analysis was also developed to estimate the wavy profile.