Charleroi's climate is typically Belgian: mild and damp, with no dramatic seasonal swings. Rain falls throughout the year; summers are warm without being hot (around 22°C in July), winters are cold and grey.
Spring and early summer (May to June) offer the most pleasant weather for walking the Ville-Haute and visiting outdoor sites. The Bois du Cazier is worth visiting any time of year — the museums are enclosed.
The Charleroi Urban Film Festival takes place in autumn and screens work in unusual locations around the city, including some of its industrial heritage sites. The festival reflects the city's self-aware relationship with its reputation and is worth checking if you visit in that season.