The paper presents an experimental study on creep and shrinkage of concrete both at variable and constant ambient conditions. The considered variable ambient conditions correspond to the natural climatic variations present in Belgium. The following parameters were examined: period (season) when the concrete was cast and loaded, cement type and concrete composition. Both sealed and unsealed cylindrical specimens were used. The experimental results show that both the 'season' in which the concrete was cast and the 'humidity cycles' influence the shrinkage deformation. The creep coefficient, however, is mostly dependent on the 'season'. Two concrete creep and shrinkage models, available in literature, i.e. the model in Eurocode 2 (EC2) and the B3-model of ACI, have been used to predict the results of the reference specimens (constant ambient conditions).