Why is the weather of the Napa Valley so great for growing grapes?
In the big picture, the Napa Valley has 32″ 36″ of rain on average per year, primarily during the months of November through April. This amount of rainfall completely satisfies the water needs of the vines. Dry farming requires 16″ 20″ annual rainfall to sustain the vines through the long dry spell during growing season (May October), especially during the ripening period (July September). During the Summer and early Fall, the Napa Valley s warm days are accompanied by cool nights. It is not unusual for there to be a temperature swing of 40 to 50 degrees from the daytime high to the nighttime low. These cool nights help to preserve the acids in the grapes leading to a more balanced wine.
