Regression of winter NAO onto summer phenology changes. Regression of the winter NAO index onto the three phenology metrics defining the summer warm period at each grid location in the study area for phenology lagging the NAO by 0 through 4 years. The units of the regression are in days. The inserts in each figure provide the spatial pattern of the associated p value of the coefficient. DOI: https://doi.org/10.1525/elementa.240.f10