Fig. 9: Average 10-day backward trajectories and boxplot of the extreme temperatures for six clusters.

a The air mass trajectories of extreme warm events in summer during 1973–2020 are classified into six types with respective proportions in brackets. b Boxplot of extreme summer temperatures for six clusters. The red center lines are the medians. The vertical dashed lines (whiskers) indicate the variability outside the lower and upper quartiles. The red crosses represent outliers.