A laboratory investigation was conducted to characterize surface features of textured geomembranes as a function of temperature using white light optical interferometry. Five types of HDPE geomembranes from different manufacturers were tested. The textured geomembranes included cast-extruded, co-extruded, and impinged products. Specimens were heated and cooled using a thermal stage attachment for the interferometer. Tests were conducted between 2 and 100°C. Amplitude and spatial texture parameters were determined. 3D images of the specimens and summary of parameters are included in the paper. Variations were observed in surface texture characteristics due to heating or cooling of the specimens. The decrease in the magnitude of the majority of texture parameters at 100°C indicated the presence of a thermal threshold, where surface texture features were affected on the macroscale. The thermal effects on the co-extruded materials in general were lower than the effects on the cast-extruded material. The changes to the surface texture characteristics have potential effects on the engineering response of the textured geomembranes.