While there are many individual weather and climate factors that can affect grape growth and wine quality (e.g., solar radiation, heat ac- cumulation, temperature extremes, precipitation, wind, and extreme weather events such as hail), growing season length and temperatures are critical aspects because of their major influence on the ability to ripen grapes to optimum levels of sugar, acid, and flavor in order to maximize a given style of wine and its quality.
Temperatures during the growing season can affect grape quality and viability in at least three ways. First, prolonged temperatures above 10◦C initiates spring vegetative growth and thus determines the start of the growing season