Engineering work is taking place between Reigate and Redhill, closing some lines.
Buses will replace trains between Reigate and Gatwick Airport.
Southern have yet to confirm how they are affected by these works.
No trains will call at Coulsdon South, Merstham, Redhill or Earlswood.
Rail replacement buses will run between Purley and Horley, calling at Purley, Coulsdon South, Merstham, Redhill, Earlswood (Surrey), Salfords and Horley.
If you are travelling with Great Western Railway or Thameslink, you can plan your journey using the National Rail Journey Planner.
If you are travelling with Southern, these changes are not currently shown in the National Rail Journey Planner, please check back nearer to the time of travel.
For helpful advice if you need to travel on a rail replacement service, including accessibility and bicycle information, please use our Rail Replacement Services page.
You can find the pick-up and drop-off location of rail replacement services by checking station signage or by searching for your station on our Find a Station page.
Please be advised that replacement vehicles may be busier than usual, and you should allow extra time for your journey.