Research on passive and low energy architecture has been recently oriented towards passive techniques in order to satisfy the cooling needs of buildings. One of the techniques which has been considered is radiative cooling. The potential of radiative cooling mainly in the United States has already been evaluated. However, a similar attempt has not been made for the southern European countries, where the weather in summer is very hot and passive cooling applications could make a significant contribution to the achievement of thermal comfort in buildings.This paper investigates the feasibility of applying radiative cooling techniques in southern European countries by presenting the results of the calculations of the sky temperature depression and of the performance of a typical radiative flat plate air cooler. These calculations were based on mean monthly weather data available for 28 southern European cities, covering a range of latitudes between 34° and 46°. Available data from some southeastern U.S. cities, have also been used. This allowed for a comparative study on the performance of radiative cooling systems between southern Europe and the southeastern United States. The results have shown that radiative cooling could be applied successfully in most south European locations.