The Dordogne is a summer destination and Sarlat its busiest node. July and August bring serious crowds — the narrow medieval streets can be almost impassably packed on a Saturday market morning in high season, and accommodation books out months in advance. If you can, avoid these months.
May, June, and September are significantly more pleasant: the weather is warm, the foliage is green or turning, and the restaurants and markets are operating at full capacity without the crush. October brings the walnut and truffle season, which adds another dimension to the market.
The truffle market runs from November to March on Saturday mornings — a serious trading event where wholesale buyers and restaurateurs negotiate over fresh Tuber melanosporum. It is not specifically aimed at tourists, but visitors are welcome to watch and buy.
Winters are quiet and cold. Many restaurants and hotels close from November to March. The medieval town in early December, when the Christmas market briefly fills the square, is worth the trip.