In this paper, inexpensive single-mode silica optical fibers were interrogated with Luna Innovations' optical backscatter reflectometer to perform distributed temperature measurements at temperatures up to 1000. Measurements of the Rayleigh backscattered signal were taken continuously to determine the amount of light that is backscattered as a function of temperature and position along the length of the fiber. These data were post-processed to determine the spectral shift in the Rayleigh backscatter signature. The spectral shift data were then calibrated to a change in temperature. This paper determines an upper operational temperature limit of 650 for the distributed measurement technique based on Rayleigh backscatter using Corning's commercially available single-mode fiber.