Reproductive success in birds is influenced by a variety of factors, many of which can be attributed to human activities such as land use or forest management. Others like weather or age of the birds are not under human control but are influential as well. From 1992-96, I examined breeding phenology and performance of Middle Spotted Woodpeckers Dendrocopos medius in northeastern Switzerland in relation to weather, territory quality and age of the birds. Timing of breeding, length of the nestling period as well as nesting and breeding success significantly differed between years. On average, incubation started earlier in years with higher daily temperatures in March-April. Neither territory quality nor the participation of 1-year old individuals in pairs influenced breeding success, whereas low temperatures and high amounts of rainfall during the nestling phase negatively affected breeding performance, which probably reflects the difficulties encountered by the woodpeckers in provisioning their young with sufficient food during periods of bad weather. These findings suggest that weather events can strongly influence reproduction even of primary cavity-nesting species, exceeding presumed differences in habitat quality at a local scale.