The ideal time to visit the National Gallery in London is typically during the shoulder seasons, which are the spring (April to June) and the autumn months (September to November). During these periods, the weather is pleasant, and the crowds are thinner compared to the summer months. The gallery can get quite busy during July and August, which is the peak tourist season in London. Visiting on weekdays early in the morning soon after opening or later in the afternoon before closing can also mean fewer crowds and a more relaxed viewing experience.

Additionally, the gallery is known to host special exhibitions and events throughout the year, so it might be worth aligning your visit with a specific display or artist that interests you. Public holidays and school breaks can see an increase in visitor numbers, so if a quieter experience is preferred, avoid these times. Keep in mind that the gallery is open 362 days a year, usually closed on 1 January, 24−26 December, so plan your visit accordingly. To ensure the best experience, always check the gallery's official website for the most up-to-date opening hours and any temporary closures before planning your visit.