Western European climate, and Pinot noir grape harvest dates in Burgundy, France, since the 17th century
from the document:
And something I did a few years ago.
Note the vertical scales are offset but per division scales are correct
And a comparison to CET
There seems to be no further analysis (more recent than 2003) which was done by:
Chuine I, Yiou P, Viovy N, Seguin B, Daux V, Leroy Ladurie E (2004) Grape ripening as a past climate indicator.
From the above it seems that grapes despite possible cultivar changes give a good proxy for temperature.
Who Dares Argue with Divine Inspiration?
2 hours ago