In this letter, a correlation between the nanoscale localized electrical properties of the Pt∕GaN Schottky barrier and the temperature behavior of macroscopic Schottky diodes is demonstrated. Although a significant improvement of the ideality factor of the diodes is achieved after annealing at 400°C, local current-voltage measurements, performed with a biased tip of a conductive atomic force microscope, revealed the inhomogeneous nature of the barrier. Its nanoscale degree of homogeneity was quantitatively described by means of Tung’s model [Phys. Rev. B 45, 13509 (1992)], allowing the authors to explain the temperature dependence of the electrical characteristics of the macroscopic diodes.