Citizens’ juries have become a popular method for engaging citizens in deliberation about complex public policy issues, such as climate action and sustainable development. Empirical evidence routinely indicates that jurors change their minds throughout the process. What is less clear is when and why this occurs and whether the causes are consistent across juries that consider the same topic but are situated within different contexts. We present evidence of opinion change in citizens’ juries through a natural experiment, contrasting three local contexts of onshore windfarm development in Scotland; viz. existing, planned, and absent. Jurors’ individual opinions of climate change, wind energy, and windfarms were measured through questionnaires at four time points: the start, following information-giving, reflection, and deliberation. Statistical examination of jurors’ responses, through paired sample t-tests, Wilcoxon sign-tests, and Generalised Least Squares regression, reveals to what extent substantive changes were associated with different phases and locational contexts. In all three juries, opinion change occurs throughout the process, on different topics, and to different degrees. While the information phase consistently influences jurors’ opinions the most, jury composition affects the magnitude and direction of opinion change, with outcomes contingent on contexts. Our findings are important for informing how mini-publics are designed and used to inform environmental policy-making at different scales.