The article discusses an instance of knowledge that failed to circulate — the application of urban climatology in town planning. This field of applied science was systematized in German‐speaking universities and cities and remains most firmly established in North‐Central Europe. In the decades after the second world war successive commissions and study groups of the World Meteorological Organization, the International Federation of Housing and Planning, the Confédération Internationale du Bâtiment and the International Society for Biometeorology sought to spread awareness of climatological factors among planners and architects worldwide. The article examines the organizations and individuals involved in this campaign, describes their meetings, publications and outreach, and assesses the disappointing impact. The legacy of this failure is considered in the context of present‐day interest in planning for carbon mitigation and climate‐change adaptation.