Abstract Fatigue damage is closely related to plastic deformation and heat dissipation, which affect the temperature of the materials. In the current research, a state-of-the-art infrared-thermography camera has been used as a nondestructive evaluation (NDE) method to investigate the temperature evolutions in both crystalline and amorphous materials during fatigue experiments. Fatigue-damage processes, such as the Luders band growth in reactor-pressure-vessel (RPV) steels and shear-band evolution in bulk metallic glasses (BMGs), have been observed in situ and analyzed by thermography. Theoretical models combining fracture mechanics and thermodynamics have been formulated to quantify the temperature-evolution processes during fatigue. Specifically, the plastic work in RPV steel during low-cycle fatigue has been calculated and the fatigue life has been predicted from the observed temperature. The prediction matches the experimental data quite well.