When is Paris least crowded, and which museums need booking ahead?

Question, scoped First trip to Paris, about four days, flexible dates. When are crowds lightest, and what has to be booked? As of October 2026. Prices and opening rules change; check each museum's official site. The answer - Lightest crowds: November through February on weekdays, excluding the Christmas and New Year holidays and school-holiday weeks. Late September and October are a good compromise between weather and crowds. July and August are the busiest and the warmest. - The Louvre requires a timed-entry reservation, booked on the official Louvre site, and is closed on Tuesdays. Go at opening time or on a late-opening evening. - The Musée d'Orsay is closed on Mondays and also uses timed tickets. - The Eiffel Tower summit sells out in high season; book on the official site. - Sainte-Chapelle and the Catacombs both have limited capacity; book timed entry. Getting around: the Métro and RER are the fastest way to move between districts. Fares and ticketing were reformed recently and paper tickets are being phased out in favour of the Navigo Easy card and mobile tickets; check the RATP site for the current options. Avoid: ticket touts outside major sites, and petition-signing and "found ring" approaches near landmarks. They are well-documented scams. Sourced Official sites of the Louvre, Musée d'Orsay, Eiffel Tower, and RATP. What would change this answer Major events (the city's calendar of trade fairs and holidays), museum renovation closures, and strikes, which are announced in advance in the French press. More planning tools: https://travel.soapbox.community and https://wiki.soapbox.community/wiki/SoapBox_Travel