The Napa Valley is neatly tucked in between two mountain ranges. To the west, the Mayacamas, which help form the boundary with Sonoma and to the east, the Vaca Mountains. Although the majority of Napa's sixteen AVAs can be found on the valley floor, quite a few are located along the foothills of both mountain ranges.
The hot Calistoga AVA located at the northernmost part of Napa is best suited to grapes such as Cabernet Sauvignon, Syrah and Zinfandel. It is a fairly recent addition, having been awarded AVA status in 2010. East of Calistoga is Howell Mountain and beyond that lies Chiles Valley District AVA. Chiles Valley is higher in elevation and has a cooler climate as a result. Like much of Napa, it is mostly planted to Bordeaux varieties. To it's south lies the Diamond Mountain District AVA, which is famous for Diamond Creek Vineyards amongst others. Diamond Mountain District, Spring Mountain District and Mount Veeder are all located in the Mayacamas and are all known for producing world-class Cabernet Sauvignon. Chardonnay, Merlot and Zinfandel are also grown in these AVAs.
Moving east into the Napa Valley from north to south we encounter: St. Helena, Rutherford, Oakville, Yountville, Stag's Leap District, and Oak Knoll District. The valley floor is made up of a combination of alluvial sediment from Dry Creek and volcanic debris, as well as pockets of gravel and clay. The unique mixture of soil types helps impart some of the characters that make the wines of this region such stand-outs. Vines dig deep into the soil for nutrients and water, which produces grapes of great concentration and flavor. It is no wonder the wines from these appellations are among the most sought after by wine lovers.
The cool Coombsville AVA is adjacent to Wild Horse Valley, which is shared between Napa and Solano County. Wild Horse Valley AVA is cool; it is higher elevation and like Coombsville, it too benefits from cooling breezes off San Pablo Bay. These factors make it the perfect place to grow cool climate grapes such as Pinot noir and Chardonnay.