EN
On the basis of term values (12 UTC) of meteorological data of seven synoptic stations in the central-west Poland heat stress index (HSI - Heat Stress Index) was calculated. During the year the heat stress of varying intensity occurred from February to November with a maximum in August. The rest of the year was dominated by thermoneutral conditions. In the period 1971-2006, and especially since 1999, becoming more frequent of occurrence days with an intensity of heat stress was so great, that pose a risk increase in body temperature (HSI > 100%). Based on the frequency of the occurrence of days with values HSI > 30% in the central-west Polad three areas with different number of days chargeable was distinguished.