Local Terroir
Geological Influences
All along the west coast of the Americas, mountain ranges tend to run roughly north-south. That’s because the coast is where the Pacific tectonic plate in the west meets the various continental plates of the east. For hundreds of millions of years, the junction saw uplift, subduction, and volcanic activity, all of which can lead to the formation of mountains.
The San Gabriel Range, however, is part of a unique set of ranges in southern California, collectively known as the Transverse Ranges because they run east-west instead of north-south. Some of the Transverse Ranges once ran north-south, but gradually moved, due to tectonic shift which dramatically, though very slowly, sheared part of the coast from the continent and rotated the freed terrain 90 degrees.
The San Gabriels, though, are relatively recent in geological terms. Of course, the rock within them can be hundreds of millions of years old. But the exposure of that rock to the surface only began around six million years ago. Then, the continuing tectonic movement caused uplift along fault lines there. The result is mountains which rise all the way up to 3,048 m (10,000 feet).
From the mountains’ genesis, water from rain and snow has been eroding and fracturing the rock, eventually carrying material downhill. As the soils are mostly volcanic in nature and come from the mountains, they hold little water or organic material. But, this loose soil does allow old vines to root very deep to reach aquifers nine meters (30 feet) or more below the surface. Thus, many of the vines can be dry farmed.
Mountains/River/other key influences
Aside from the aforementioned geological factors, neither mountains nor rivers have a significant effect on the Cucamonga AVA. In fact, because the mountains are transverse, they don’t even have a notable climatic effect. Therefore, the primary geographical influence on the area is the Pacific Ocean and its somewhat moderating impact.
Soil Diversity
The soils of Cucamonga Valley vary in granularity, depth, and organic content, depending on location and on the slope of that terrain. Beyond that though, the AVA’s soils are relatively homogenous. Their origin is the largely granitic San Gabriel Range.
Climate
The Cucamonga Valley AVA has a hot-summer Mediterranean climate. Mediterranean climates are those whose climate is heavily moderated by a large body of water. So, their summers are cooler and winters warmer than they would be without that moderation. These climates also feature long, dry, sunny growing seasons. Only 3% of the earth’s land mass falls under this classification.
Hot-summer Mediterranean climates, as opposed to warm-summer and cool-summer climates, experience average summer temperatures that are dramatically warmer than average winter temperatures. Cucamonga Valley owes its hot-summer Mediterranean climate to its relative isolation from the Pacific Ocean by both distance and mountains. Therefore, the ocean’s moderating effect is weaker during the summer than it is for more coastal regions.
The Winkler heat-summation rating for Cucamonga Valley reflects this climate. The long, hot growing season results in total degree-days during the growing season ranging between 3,501 and 4,000 F° (1,927-2204 C°). That is a Region IV climate classification on the Winkler scale. Such climates are best-suited to growing robust, black grape varieties that are slow to ripen and also grapes intended for production of sweet, fortified wines.