The northernmost grape-growing region in Chile is Atacama. This is one of the dryest climates on earth and is a terrible climate for growing anything used to make wine. Most of the grapes grown here are used for table grapes, and an Oak-aged brandy type spirit called PIsco. Pisco is usually made of Moscatel, Toronotel, and Pedor Jimenez and is the natinal spirit of Chile.
Coquimbo is the next wine region south from Atacama, and is very similar in climate. Coquimbo also produces a lot of table grapes and Pisco, but there are a few pockets of vineyards in cooler climate areas closer the Pacific. The Limari valley, for one, is exporting some wine made of international varietals like Cabernet Franc, Cabernet Sauvignon, Merlot, and Chardonnay. The main limitation there, however, is that the high heat requires too much irrigation to produce a lot of high quality wine.
The next southerly grape growing region is the Aconcagua Valley. This is the first of the main export producing wine regions in Chile. Here it is hot and dry, with temperatures in summer reaching as high as 86 degrees farenheit. The soil in the valley is generally alluvial. For the most part, red wine grapes are grown here, including mostly Cabernet Sauvignon.
Traveling further south, Casablanca is the next wine region. Casablanca is technically part of the Aconcagua Valley, but it has its own cooler microclimate due to it's higher altitude, about 1,640 feet above sea level. Casablanca often has cool morning fog, and a slow ripening season with almost constant cloud cover. White grape varieties do best here, with Chardonnay taking the lead. There are some red grape wines produced here, but most of the fruit brought in from the Maipo valley to the south.
The Maipo Valley is the oldest and most well-known wine producing area in Chile. It is a small area, with only 7,000 hectares under vine, in the Central Valley, which is just south of Santiago. The most common grapes here are Cabernet Sauvignon and Chardonnay. Merlot and Sauvignon Blanc are also grown to smaller extents. There is very little rain here, requiring the use of prudent irrigation. The soil is sandy and alluvial with calcium deposits left by the Maipo river.
Just south from the Maipo Valley is the Rapel Valley, known for producing full-bodied, age-worthy red wines. Cabernet Sauvignon is the most comm-on grape grown here. The climate is sunny during the summer with cool nights and moderate rainfall during the winter. The soil is made up of clay and calcareous Tuffeau, a type of soil common in the best wine producing areas of the Loire Valley in France. Because of the ideal soil and climate conditions here, investment in the area has been sky rocketing in the past 10 years.
Further south, the Maule Valley is the the largest wine producing area in Chile, with about 30,000 hectares under vine. The Pacific ocean lends cooler temperatures, and rainfall is a constant threat. Summers can be fairly warm during the day, with temperatures reaching up to 88 degrees fareneheit. The nights, however, are much cooler, which leads to a good balance between sugar and acidity in the grapes. Pais, the mission grape, is the most common varietal here. Some wineries in the subregion of the Curicó are starting to plant more international varities, with many thinking that Merlot may become quie successful. Experimentation with Chardonnay and Pinot Noir has also begun.
The southernmost wine producing area is Bío-Bío, which has 13,000 hectares under vine. Most of the wine produced here is intended only for local consumption, and is split evenly among red and white wines, produced from Pais and Moscatel. This region generally has too much rainfall, low temperatures, and too little sunlight to produce export-quality wine.