Mondragon cliffs. Climate The area straddles the Mediterranean and the continental climatic regions where in this part of France the climatic transition is rapid, winter snow being frequent in Montélimar but rare some 20 - 30 kilometers further south. In this transitional area that constitutes the northern limit of Provence, the climate in Saint-Paul is more typically Mediterranean than the slightly cooler areas dominated by Lance Mountain in the Drôme provençal. The Tricastin has a climate which is mostly Mediterranean augmented by the mistral in winter, and a marked increase in aridity in summer. Winters are generally milder than in the northern part of the Drôme and in the Ardèche but cooler than in Provence where the difference is two to three degrees Celsius on average. Temperatures can thus be very hot in summer and the downpours brutal, the Tricastin valley being located as it is between the Cévennes Piedmont (in the Gard and Ardèche departments) and the town of Nyons in the Baronnies (Drôme and Vaucluse). Economy Agriculture Wine This is a wine-growing region. The wine Coteaux du Tricastin AOC is produced in the area, was classed VDQS in 1964 and achieved AOC status on . Mushrooms The Tricastin truffle is protected by AOC certification since 1978, it ranges over 68 communes in the Drôme and 15 communes in the Vaucluse. In order to meet the AOC designation, the Tricastin truffle requires sterilization during the first boil and only with T. melanosporum. In this region, as in others, truffle growers got together and formed professional associations such as the Drôme des Collines or the Syndicat général de la truffe noire du Tricastin with headquarters at the Maison de la Truffe et du Tricastin in Saint Paul Trois Châteaux. Energy The Tricastin nuclear power plant, situated in the heart of the Tricastin valley since 1974, is a pressurized water reactor and one of the most important nuclear plants in France. It straddles the communes of Saint-Paul-Trois-Chateaux, Bollène, Lapalud and Pierrelatte. It is the chief industrial plant in the Tricastin valley area and supplies the energy needs for the departments of Ardèche, Drôme, Vaucluse and the Gard. The Donzère-Mondragon dam, a major development in French industrial history, is located on the Donzère-Mondragon canal. Tourism Significantly improved by construction during the 20th century, the Tricastin valley is criss-crossed by Route nationale 7 (RN7), freeway A7, the TGV Méditerranée high-speed train, and a