In this article, we report on an experimental research on the probability density function (PDF) of temperature measured in the wake of a circular cylinder slightly heated and its relationships with the turbulent mixedness under different Reynolds numbers (1200-8600). The temperature is measured by a probe of cold-wire with 0.63-m in diameter. Results show that the temperature PDF varies significantly with location in the wake. An increase in Reynolds number speeds up this variation, particularly accelerates the evolution from totally non-Gaussianity to near-Gaussianity along the wake centreline.