We introduce the thermosurvey dataset, a comprehensive collection focusing on the thermal comfort, heat-related experiences, health, socioeconomic status, and perceptions of older adults (aged 65 and over) in Warsaw and Madrid. The two cities differ greatly in their heat experiences, but due to climate change, both face increasing temperatures. The study aimed to understand how heat affects cities’ older adult population and how we can better adapt to rising temperatures. We call the study a thermosurvey because it connects traditional survey data with temperature and humidity measurements done before, after and during the interview, offering a holistic view of the participants’ thermal environments. The dataset can be used to better understand thermal comfort, the interplay of health and heat experiences, and the relationship between experiences and climate change views. We hope our data will enable scholars to analyse the impact of climate change on older adults and to develop strategies to help them adapt to a warming climate.