The Urban Heat Island (UHI) phenomenon is a leading cause for concern, yet effective mitigation action remains limited. A knowledge circulation failure has long been suggested to exist between scientists and practitioners, though this hypothesis was rarely systematically examined. Here, we investigated this gap using English-language Wikipedia, a pivotal channel for knowledge dissemination. Using a mixed-method diachronic analyses of text, structure, edits, and bibliometrics of the UHI Wikipedia article over its 20 years existence, we evaluated how this field and the science behind it were translated into the popular open-source encyclopaedia. While overall utilizing reputable sources, the article’s coverage of the UHI phenomenon and its mitigation exemplified knowledge gaps by relying on outdated literature and absence of review articles. Specifically, the mitigation section lacked a clear hierarchy of their effectiveness while excluding some key mitigation concepts. Despite intense editorial activity in its early years, the article stagnated from the mid-2010s to early 2023, leaving it disconnected from ongoing scientific efforts. Our findings highlight concerning disconnects between academic advancements and their translation into actionable information for the public and policymakers. Failing to accurately represent mitigation measures poses a risk of perpetuating outdated strategies and impeding progress towards effective climate mitigation.