Montepulciano is enjoyable throughout the year, but summer (July–August) brings large crowds and high prices to what is a small town with limited capacity. Spring and autumn are the best seasons: April and May offer wildflowers on the surrounding hills, September and October the grape harvest, golden light, and the Bravio delle Botti — the town's barrel-rolling race on the last Sunday of August, which draws large local crowds.
The Cantiere Internazionale d'Arte festival brings contemporary music and performance to Montepulciano in July and August, making those months particularly vibrant culturally if you can tolerate the crowd levels. Winter is quiet but not grim — the town functions normally, the cellars are open, and you will have the streets largely to yourself.