The vintage of a wine is about the last thing that most casual wine drinkers look for when choosing a bottle to bring home to go with dinner. However that bit of information can provide huge insights to the taste, aroma and body of the wine inside. A vintage wine is one made from grapes that were all, or primarily, grown and harvested in a single specified year. In certain wines, it can denote quality, as in Port wine, where Port houses make and declare vintage Port in their best years. From this tradition, a common, though incorrect, usage applies the term to any wine that is perceived to be particularly old or of a particularly high quality. In the United States, Europe, Australia and New Zealand a “vintage wine” must be 85% same-year content. Meaning 85% of the grapes had to be grown in the vintage year. If the wine is the United States and is produced in an American Viticultural Area (AVA), Napa valley, for example the standard is 95%. Technically, the 85% rule in the United States applies equally to imports, but there are obvious difficulties in enforcing the regulation.
The best vintages in any region have a growing season that produced consistently warm temperatures day to day and cool nights. However, no extremes to these temperatures, no spikes of hot days or cold nights with frost. Grapes do not tolerate rapid change in temperatures as a rule, but spikes to high temps are very problematic as the fruit can quickly become overripe. On the other end of the temperature spectrum, frost can cause just as much if not more havoc. Grapes can be devastated by frost from the point the vine blossoms until harvest. Either a late frost in the spring or an early frost in autumn can ruin a crop for a year. Vintages from hot weather years may have higher alcohol content, and have a lower acidity. Cold weather years tend to produce a lighter body wine with higher acidity. If it is too cold the grapes will not ripen enough to produce wine.
Of course there are other weather events that can affect wine production. Late season rains can cause delays in a grower’s ability to harvest the fruit. When the grapes are ripe and have formed thick plump bunches, rain can cause mold and mildew to grow. What might be the most devastating event for a grower; hail can ravage a crop in minutes. This may not only ruin one year’s crop but can beat the vines and cause long term damage.
I know a lot of weather forecasters that may not be as obsessed with the weather as some wine producers.