Atmospheric conditions strongly inﬂuence ecological systems, and tools that simplify the access and processing of atmospheric data can greatly facilitate ecological research. We have developed RNCEP, a package of functions in the open-source R language, to access, organise and visualise freely available atmospheric data from two long-term high-quality data sets with global coverage. These functions retrieve data, via the Internet, for either a desired spatiotemporal extent or interpolated to a point in space and time. The package also contains functions to temporally aggregate data, producing user-deﬁned variables, and to visualise these data on a map. By making access to atmospheric data and integration with biological data easier and more ﬂexible, we hope to facilitate and encourage the exploration of relationships between biological systems and atmospheric conditions.