We study the behaviour of sun and sand tourists in Spain in relation to the prevailing summer weather conditions. To do so, we built up an image bank, supplied by web cameras and Argus video monitoring systems, located at 8 observation points along the Spanish coast. We then used a method of qualitative counting based on establishing use density categories. Once classified according to the established densities of use, the images were related to several weather variables and comfort indices, and the most appropriate thresholds for sun and sand activities were established. We thus confirmed that beach use is fundamentally governed by solar radiation (aesthetic aspect) and the maximum temperature and PET (comfort). The application of the thresholds to determine the level of beach use throughout the year could lead to anticipating the tourist season calendar. This could help to offer and administer basic tourist resources correctly during the tourist season and thus enhance enjoyment of the beaches, the provision of services and the safety measures. These aspects are fundamental when it comes to maintaining and improving the use of such leisure and recreational spaces, as well as for meeting tourist requirements and conserving the elements that allowed such activity to appear and flourish.