Chantilly is at its best from late spring to early autumn, when the gardens are in full leaf and the equestrian shows in the Grandes Écuries run on their full schedule.
The two biggest dates of the year are the Prix du Jockey Club (French Derby) on the first Sunday in June, and the Prix de Diane (French Oaks) two weeks later. Together they make up the early-June racing peak — the town fills with racing crowds, hotels and restaurants book out weeks in advance, and the Hippodrome itself becomes the centre of attention.
Outside racing season the château and its grounds are open year-round. The collection is closed on Tuesdays in every season. In winter the gardens are bare and many of the outdoor restaurants close, but the museum is uncrowded and tickets need no advance booking.
The Nuits de Feu, the Chantilly International Fireworks Festival, happens once every two years in June and is one of the most spectacular events of its kind in Europe — competitors from around the world stage 30-minute pyrotechnic shows over the canal.