Comparing winter temperatures for 1909-1938 (blue curve) and 1987-2016 (red curve). In 1909-1938, the June 1 temperature averaged 8.6°C, but by 1987-2016 temperatures this low did not occur, on average, until June 16. Similarly, winter ‘ended’ in 1909-1938 with a daily temperature of 8.8°C, but this is now reached much earlier on August 14. (Note: The red curve is the same as that part of the red curve within the dashed box of Figure 1).