The increasing use of outdoor housings for temperature-sensitive apparatus, coupled with the growing interest in adhesive-bonded structures for building constructions, aircraft, armaments, etc., has prompted a growing concern over the effects of solar heating on such structures. Vagaries of local weather conditions provide little cause for confidence in short-term outdoor exposures as a means for determining extremes of temperatures which may occur in structures over extended periods of time and in a variety of geographical locations. Potential minimum temperatures can be established solely on the basis of observed minima for the area concerned, taken from records of the Weather Bureau. Maximum temperatures of exposed structures are, on the other hand, subject largely to the absorption of thermal energy from the sun, a quantity which can vary widely due to a number of natural and manmade factors. Much has been written regarding the intensity of solar radiation and its effect on climate, but relatively little information is available to the designer and the materials engineer regarding the temperatures which may occur in structures due to solar heating. The little that does appear in the literature generally concerns specific items, for example, wooden aircraft wings, roof structures, transformers, etc. In this paper, the author will review the more important factors involved in solar heating and will summarize available temperature data on various exposed structures from published and unpublished sources. Following this, an attempt will be made to suggest temperature maxima for consideration in design and in simulated exposure tests for sandwich and other structures which may be exposed to the weather.