Here we present and analyse over 1 million historical (1950 - 1960) temperature and precipitation observations from 37 weather stations in the Democratic Republic of the Congo, recovered from paper archives, which have until now been unavailable to the research community. Among others we find an increasing frequency of hot extremes and a decreasing frequency of cold extremes with each successive decade, with the most recent decade exhibiting nearly twice as many hot days per year and fewer cold days compared to the earliest decade. This analysis of rescued weather data highlights the urgent need to close the knowledge gap on climate trends in the Congo Basin and other data sparse regions.