Clear communication in participatory research is commonly approached through linguistic, cultural, ethical, and accessibility considerations. However, in this article, we argue that an additional and often overlooked dimension, environmental context, plays a crucial role in shaping interaction and engagement, influencing participant’s comfort, attention, and willingness to engage, and ultimately the effectiveness of the research intervention. Drawing on an exploratory case study from the 2025 European Researchers’ Night in Barcelona, we demonstrate how an intervention designed using clear communication strategies, including user profiling, gamification, accessible materials, and structured interaction phases, was nonetheless derailed by extreme weather conditions. A prolonged heatwave, high humidity, the urban heat effect, and the arrival of storm Gabrielle significantly affected participant’s levels of comfort, attention, and willingness to engage, disrupting fundamental conversational principles such as cooperation and relevance. This experience highlights how environmental factors can heighten cognitive strain and compromise effective communication. By analysing this failed intervention, we propose expanding current clear-communication and participatory design frameworks to formally include environmental context as a crucial element in both planning and reporting of research activities.