Abstract In 1639, the German naturalist Georg Marcgraf established the first astronomical observatory in the Americas, located in Recife (Brazil). There, he made the first daily systematic meteorological observations of wind direction, precipitation, fog, and thunder and lightning from 1640 to 1642. We outline the circumstances that led to this observatory being established and analyze the observations. The range of values obtained from all the variables recorded by Marcgraf corresponds well with Recife’s current climate. However, wetter-than-normal conditions were recorded during 1640, while anomalous concentrations of foggy days occurred from May to December 1641. We hypothesize that these anomalous record foggy days could be associated with the highly explosive eruptions of the Komagatake and Parker volcanoes, both in 1640.