Abstract Background Air temperature is a relevant environmental determinant of hospitalization and mortality. Less known is the prevalence of at-home thermal discomfort and its associations with health indicators. This work aimed to characterize the association between thermal discomfort and self-reported non-communicable chronic diseases in adults living in the municipality of Lisbon. Methods Observational cross-sectional study with data collected through individual telephone interviews, with a non-probabilistic stratified (by gender, age, education, and area of residence) sample. Logistic regression models were used to estimate effect sizes, controlling for age, gender, educational level, and morbidity indicators. Results Overall, 855 adults (25+ years old) living in the municipality of Lisbon participated in the study. Only respondents who reported to be 10+ hours per day at home were included in the analysis. The sample was balanced for genders (55,2% female), with an average age of 53,4 years (SD = 17,0; maximum age=93 years old), and 40,2% (n = 356) not having a higher-level education. About three-quarters (74,2%; n = 552) reported feeling thermal discomfort at home and 56,9% (n = 414) reported having at least one non-communicable disease diagnosed. When considering the sample's most prevalent self-reported chronic diseases, a significant association with thermal discomfort was found for asthma and hypercholesterolemia (chi-square=4,08; p=.004; and chi-square=4,87; p=.027, respectively). After adjusting for sex, age, educational level, area of residence, and other self-reported morbidities, asthma was found as a significant predictor of thermal discomfort (OR = 3,03; 95% CI: 1,03-8,90). Conclusions These preliminary results suggest that some chronic diseases may have an unequal impact on thermal regulation and comfort. This is an important message also for those responsible for the development of policies against energy poverty. Key messages • At-home thermal discomfort is a relevant indicator to consider when monitoring chronic diseases and urban health. • Suffering from chronic diseases may have a relevant impact on thermal discomfort and this should be taken into account when defining policies against energy-poverty.