The effects of weak atomic vibrations on extended X-ray absorption fine-structure (EXAFS) spectra are discussed from a phenomenological perspective. Attention is focused on single-scattering paths and in particular on the first-shell contribution, in terms of bond expansion, parallel and perpendicular mean-square relative displacements, and distribution asymmetry. The main differences with respect to Bragg diffraction are stressed. Some theoretical methods that have been developed to simulate thermal effects on EXAFS are reviewed.