The Discomfort Index (DI) was found to be an accurate expression of the atmospheric evaporative (cooling) power, and hence the heat load. It conveys the relevant climatic conditions in summer in physiologically significant terms. From 22-24 units a slight heat load exists, from 24.1-28 the heat load is moderate and above 28.1 a severe heat load exists. The heat load during the month of August was analyzed for 2 towns in Israel: Tel-Aviv (in the coastal plain) and Beer-Sheba (in the northern part of the desert). On the basis of this example a method is suggested to express summer climate as daily hours of heat load. Information about heat stress can be conveyed in terms which are sïgnificant physiologically and meaningful to the public.