Relationships between the Fregoni bioclimatic index (IF) and wine quality

The Fregoni bioclimatic index (IF) considers the daily temperature range during the ripening month and the number of days with temperature below 10°C. The world areas characterized by large daily temperature ranges produce, as a rule, great wines, like for example Napa and Sonoma valleys in California, Chile and the Cape province in South Africa. A worldwide survey was carried out in order to assess correlations between the IF and the wine quality. The wine quality, for the same wine type during different vintage years, was expressed as hedonic evaluation (by a score up to 100). Spain, Switzerland, Germany, Romania, Canada, Chile and South Africa were investigated. The IF (vintages 2000-2005) ranged from 300 to 4,000 in the Valencia region, while in Navarra (vintages 1996-2005) from 300 to 3,400. In Germany the IF (vintages 1996-2005) ranged from 300 to 6,500, in Switzerland from 1,300 to 10,800, in Romania (vintages 1990 – 2005) from 200 to 7,000, in Canada (vintages 1996-2005) from 300 to 2,000, in Chile (vintages from 1999 to 2004) from 7,600 to 16,200, in South Africa (vintages 1994-2002) from 260 to 470. In cool climate countries like Germany and Switzerland, the best vintages corresponded to intermediate IF values (2,000-3,000, in Germany, and 5,000-6,000 in Switzerland), while in a warmer country like South Africa the best vintages corresponded, as a rule, to the highest IF (400).