Abstract A general algorithm is described for estimating average monthly solar radiation in cal cm −2 day −1 received on mountain slopes that uses basic topographic and climatic information for input, i.e. latitude, elevation, slope aspect and orientation, and average monthly data for ambient temperature, relative humidity and total precipitation. The algorithm is an extension of the methodlogy developed by Lui and Jordan, Klein, and Bonan. We have tested our method against independent data from 69 meteorological stations throughout the northern hemisphere provided by Müller and Zeller. The stations were selected to represent different latitudes, climate zones and elevations. The test showed that the algorithm predicts quite accurately seasonal patterns of solar radiation from the subpolar region down to the tropics and thus can be used with ecological simulation models (e.g. gap-phase succession models or regional landscape models).