Abstract This paper discusses weather observations of Moravian missionaries in Greenland in the long 18th century, placing them in the broader context of their missionary work at Neu-Herrnhut and other stations as well as their comments on the natural world. Some of their climate-related remarks and measurements were published and discussed in print, notably in David Cranz’ History of Greenland and a number of scholarly reviews at the time. These publications are compared to and complemented by data retrieved by the authors from unpublished source material in the Moravian Archives in Herrnhut, Germany, demonstrating that the Moravian diaries can fill in significant gaps in Greenland’s weather charts before systematic measurements were introduced in the 19th century. Their special interest for climate studies is underscored in conclusion, in particular their observations of extreme climate events that can allow us to better characterise the amplitude and geographical extent of such events and to compare them with climate model simulations in order to better understand the respective roles of external (volcanism, solar activity) and internal (atmospheric circulation) forcings and the impacts of potential feedbacks within the ocean–atmosphere system.