Idaho Wine Commission
From a purely geographical standpoint, area vintners insist, southern Idaho offers ideal growing conditions.
Vinifera, or wine grapes, actually thrive in this distinctly four-season climate, The characteristic cold winters, which might at first seem a disadvantage, are in fact quite conducive, allowing vines to go dormant, to rest and conserve important carbohydrates for the coming season, while ridding the plants of bugs and discouraging disease.
In addition, the region’s summer combination of cold nights and warm days serves to balance grape acids and sugars favorably. In the 30*-40* diurnal temperature variations typical of this higher elevation—swings from 1–* to 65* are common—sugars remain high , nurtured during the long day by the abundant sunshine, while acids are maintained at favorable levels by comparatively cool evenings.
These natural acids, important for the wine’s taste and longevity, can be difficult to maintain in, for example, the warmer California climate.
Adequate sugar, on the other hand, is often the obstacle in Oregon, where early rains absorbed by the grapes and vines in the final stages of ripening dilute the fruit’s natural levels of the substance.
Because such potentially ruinous precipitation is also responsible for assorted other agricultural woes, including mold and rot, the Snake River Valley’s lack of rainfall is considered a plus; here, water is one element that can be controlled by the grower through irrigation, according to calculated timing.