Valais offers the driest climate surrounded by the barrier of the Alps, of all Swiss wine-producing regions. The "foehn", a temperate wind which accelerates ripening, is also known for an significant climatic factor.
January: -0.2°C / 32°F
July: 20°C / 68°F
Rainfall: 575 mm/yr. (22.4 in.) at Sion
Drier than any other region
Annual hours of sun exposure: 2010 hrs at Sion
This is a bit less than in Ticino, but more than in other regions.
Most Valais vineyards, located within the area of 470 and 700 m. (1542-2300 ft.). Those of Visperterminen, among the maximum in Europe (1100 m /3600 ft.), are brilliant.
The combination of the geological upheavals, the receding glaciers and the alluvial deposits of the Rhone and mountain torrents comprises the great variety of soil compositions. Depending on the soil, the principal Valais white wine, Fendant, made from Chasselas grapes, ranges grippingly from one area to another.
Martigny - Fully: (granite)
The granite soils of Martigny and Fully, barely or not at all calcareous, are perfectly located for Gamay.
Created by torrents carrying earth, silt and minerals from the mountains, the alluvial soil of Chamoson and Leytron offer the optimal base for the harvesting of the Sylvaner grape (Johannisberg wine).
Saillon and Ardon, generations of winegrowers have covered the soil with up to 15 cm (6 in.) of gravel, in some vineyards, to hold the heat and minimise evaporation.
In the Sion area, the soils compose largely of schist, the rocks of which look like millefeuille pastry.
Limestone is everywhere in central Valais, particularly dominant at Sierre (Siders) and Loeche (Leuk).