Questionnaires exploring tourists' perceptions of ideal climatic conditions are argued to be a more suitable data source for the development of tourism climate indices than the utilization and integration of expert opinion and pre-established thresholds. This assumes that those tourist respondents can accurately quantify meteorological conditions at a given point in time, and effectively discriminate between meteorological thresholds of suitable and unsuitable conditions. For variables such as rainfall and sunshine hours, this assumption is fairly reasonable. However, where tourists' perceptions, captured through questionnaire responses, are used to set thresholds for air temperature and thermal comfort, it is important to determine whether those perceptions are valid. Previous studies contest this, indicating considerable differences in perceptions of heat thresholds based on terminology, nationality, destination, and time of the year. In this study, a benchmarking exercise is performed comparing perceived temperatures and thermal comfort to measured values, through questionnaires administered to 984 adults in South Africa. Findings indicated that while 19.9% of responses are within 1 °C of measured temperatures, up to 12.8% of respondents perceive temperatures as being at least 6 °C higher or lower than the measured values. There are no clear geographic or demographic variables that effectively discriminate between accurate and inaccurate responses. When asked to classify their level of thermal comfort, as opposed to quantifying temperatures, results aligned more closely with measures and classifications of effective temperature. Based on these results, we argue that greater caution should be applied when using temperature thresholds derived from questionnaire data in developing and calibrating any biometeorological indices, and focus instead should be placed on catergorized levels of self-reported thermal comfort in environments where raw meteorological conditions are measured.