The paper is concerned with a physically nonlinear behavior of piezoelectric rods. Such rods are often employed as transducers. We evaluate the effect of a uniformly distributed temperature on vibrations of a piezoelectric rod polarized in the axial direction and subjected to a harmonic (periodic-in-time) electric field. We conclude that temperature can significantly affect vibrations of a physically nonlinear transducer in a broad spectrum of frequencies. It is also shown that physical nonlinearity has a strong effect on the dynamic response of piezoelectric rods to alternating electric fields, especially in the vicinity of the resonance frequency and at high power fields.