People often ask why wines from Europe generally have less alcohol than California wine. The quick answer is California’s consistently warmer climate. High temperatures, and longer summer-like conditions, raise the sugar level in grapes, which is directly related to alcohol. This allows grapes to hang on the vine longer, develop more complex flavors, and with that comes higher sugar content: The higher the sugar in the grapes, the higher the alcohol in the final product.
However, the trend in California wine has been to make bigger, more alcoholic wines. Some believe the driving force is from influential wine critics who have awarded high scores to this high-alcohol style in the last 10 years or so. That motivates some winemakers, or winery owners, to aim at winning these scores by imitating the style that the critics prefer.
But the problem with high alcohol content comes only when the alcohol overwhelms the wine. If a wine has intense fruit, strong tannic structure and good acidity, then it also needs a high alcohol level to balance it. Too many wines have been made that have the high alcohol, but everything else is hidden by the alcohol. A good example is when a burning sensation is felt on the lips and palate: This is evidence of wine dominated by its alcohol. In these instances, some wineries will actually take steps to reduce the alcohol in their wine by putting it through a process that lowers the overall percentage of alcohol.
So, balance is the key to a good wine, whether it has 12% alcohol or 16%. A good quality fine wine can have either amount, as long as it is balanced with all other components.