Pistoia is a year-round destination, but spring (April to June) and autumn (September to November) are the most comfortable. The city avoids the crushing summer crowds of Florence and Lucca, which means even July and August are manageable by Tuscan standards, though temperatures can reach 35°C.
The most distinctive local event is the Giostra dell'Orso (Joust of the Bear), a medieval jousting festival held in the Piazza del Duomo on 25 July. It is genuinely popular with local people rather than just tourists, and the city fills up significantly in the days around it. If the festival is not a draw, this is a period to arrive early or book accommodation well ahead.
The Wednesday and Saturday markets on the Piazza del Duomo and surrounding streets are worth timing a visit around — they sell produce, local food, and household goods rather than tourist items, and give the piazza a very different character from the usual tourist-centre atmosphere.