This dataset was generated to investigate urban heat and thermal perception across five neighborhoods in the Barcelona metropolitan area. In collaboration with 14 non-academic partner organizations, we conducted a series of citizen science campaigns involving 439 residents as co-researchers engaged throughout all stages of the research process. Participants—residents of areas classified as highly or very highly climate-vulnerable—identified 210 public outdoor sites relevant to their daily lives. These locations were subsequently characterized using a range of spatial and environmental indicators pertinent to urban heat island effects, urban health, and climate resilience. Over the course of 48 thermal walks, participants carried portable, low-cost sensors that continuously recorded air temperature, relative humidity, and geolocation, resulting in 296286 processed microclimatic data points. At pre-defined sites, individuals completed standardized surveys to report their Thermal Sensation Votes and Thermal Comfort Votes, yielding 5169 self-reported entries. Sociodemographic data were also collected to further contextualize participants’ responses. The resulting dataset integrates objective environmental measurements with subjective perceptions of heat, enabling point-by-point analysis of thermal experience within the urban fabric. It offers a novel, multi-dimensional resource to support research on heat, thermal inequality, and the experiential dimensions of climate vulnerability, and is intended to inform evidence-based decision-making in urban planning, public health, and climate adaptation.

This data repository also includes the Heat Chronicles contributors as authors, referring to all individuals who participated as co-researchers and consciously contributed to the project. They are children and adolescents attending summer camps, children and adolescents residing in shelter homes, primary school students (aged 10–11 years), secondary school students (aged 14–15 years), secondary school students receiving specialized educational support (aged 14–16 years), educators and teachers, mothers of toddlers, public library users, shopkeepers and older adult groups (women and mixed) participating in community activities.Their contribution was possible thanks to the active involvement of 14 collaborating community organizations across the five locations in the Barcelona metropolitan that facilitated the Heat Chronicles implementation in the territory: Fundació Comtal (education and support for children, adolescents, and young people in situations of social vulnerability), Canòdrom (Center for Digital and Democratic Innovation), Casal de Barri Congrés–Indians (Community Center), Fundació MAIN (Shared Schooling Unit – Specialized Education), Servei Residencial d’Acció Educativa Congrés–ISOM (Shelter homes for children and adolescents), Unió de Botiguers (Shopkeepers’ Union), Taula Comunitària del Barri del Congrés–Indians (Community Assembly of the neigbhorhood), Biblioteca Josep Janés (Public Library), Escola Pep Ventura (Primary School), Escola Bressol Nova Fortuny (Kindergarten), Procés Comunitari Intercultural (Intercultural Community Process), Associació Educativa Itaca (socio-educational organization promoting equal opportunities for children and young people), Institut La Ribera (Secondary School), and Escola La Guàrdia (Primary School). Team members, that, in addition to authors, have contributed coordinating and/or offering support to the campaigns: Maday Rivero, Iván Casanovas, Rebekah Breding, and Martín F. Díaz (OpenSystems group members), and Ferran Capell, Roger Jové, Uriel Merino, Ulises Fabián Náger, Víctor Ramos, César Recacha, and Oriol Riera (students from the Faculty of Physics at the University of Barcelona).

Heat Chronicles is partially funded by SENSE from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 101058507 and by OPUSH from the ERA-NET Urban Transformation Capacities (ENUTC) program under Grant Agreement no. 101003758. The study was also partially supported the Ministerio de Ciencia e Innovación and Agencia Estatal de Investigación MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe", grant number PID2022-140757NB-I00 and by MCIN/AEI/10.13039/501100011033 and European Union NextGeneration EU/PRTR, grant number PCI2022-132996.