Lyon is a year-round city. The Fête des Lumières in early December — when the entire city is illuminated with light installations in a tradition dating to 1852 — is the most spectacular single event in the Lyon calendar and draws around two million visitors over four evenings. Book accommodation months in advance if you plan to be there. June and July bring the Nuits de Fourvière festival, with open-air performances in the Roman theatres. Spring (April–May) and early autumn (September–October) are the most pleasant for walking. Summers are warm to hot (25–32°C), with the occasional August heatwave; winters are grey and damp, though mild by northern European standards.