April, July, August and October — UK school holidays and October half-term with the Howl'o'ween season.
Quietest months
May, June and September — term-time weekdays, when much of the park is a walk-on.
Local knowledge: The zoo half is genuinely good and absorbs the peak hours well — ride mornings, animals at midday, ride again after 3 PM.
How this is worked out
Each day starts from how that weekday normally runs at Chessington, learned from our own recorded wait snapshots as they accumulate, and is raised for public holidays and school-holiday periods. It is a forecast of relative busyness, not a promise: a 3 means a day that usually runs quiet for this park, not a guarantee of short lines. The further out a date sits, the more it leans on the weekday pattern alone.
Want the live picture instead? Chessington wait times has today's queues, the hour-by-hour curve and what counts as a normal wait here. Planning a specific day? Open the planner and it will build a route around these crowd levels.