Spoleto is at its liveliest in late June and early July during the Festival dei Due Mondi, when the old town fills with performers and audiences from across Europe and North America. Accommodation books up months in advance and prices spike. If you want the town to yourself, avoid the festival and come in May, September, or October — the weather is pleasant, the restaurants have room, and the streets are quiet enough to hear your own footsteps on the cobblestones.
Summer (July–August) is warm and sunny but can be crowded and hot at midday. Spring brings wildflowers in the surrounding hills. Winter is cold but the town is fully functioning and atmospheric — the Duomo looks particularly good in grey light.