Fluctuations of winter surface temperature significantly affect the timing and length of the growing season at the mid- and high latitudes with consequent impacts on the water and carbon budgets of terrestrial ecosystems. Changes in spring phenology across the European continent are analyzed in detail searching for possible connections with the North Atlantic Oscillation (NAO). Due to its impact on the regime of winter temperatures, the NAO is found to explain part of the fluctuations existing in the dates of first leafing, blooming, and pollen season start. Some climatic variables are studied as possible predictors of these phenological events.