The changes are due to engineering work and will affect trains from Monday to Friday (June 23 to June 27).
We have outlined and simplified the details so you can plan your journey this weekend.
Engineering work is taking place between Balham and Coulsdon Town, closing some lines overnight.
From approximately 11.30pm on Monday to Thursday evenings until 5.30am on Tuesday to Friday mornings, trains between London Victoria and Gatwick Airport will run to an amended timetable with extended journey times.
