For 12 selected synoptic stations of the Greek Weather Service, the daily 12 UTC values of the thermal index Predicted Mean Vote (PMV) were calculated for the years 1980 to 1989. The locally varied occurrence of diverse thermal sensation and particularly of strong heat stress were analysed in relation to the human-biometeorological significance. With the help of a statistical model, PMV values of individual stations were transformed into a high-resolution bioclimatic map. The map presents the average annual number of days with at least strong heat stress (PMV > 3.0).