Heavy rainfall is causing major disruption to Gatwick rail services, with Southern, Thameslink and Gatwick Express journeys all affected.
Rail operator Southern has told passengers not to travel between Brighton and Gatwick and warned services from London to the airport are also affected.
The operator said: "Alternative routes to reach your destination are limited, so you should make your own way to your destination. Please be mindful that roads will also be suffering from the increased rainfall.
"You should strongly consider making private travel arrangements in order to get to your flight in time. London to Gatwick Airport services will be affected, but to a far lesser extent."
Southern also said no services are operating between Haywards Heath and Three Bridges due to flooding in the Balcombe area.
Attempts are being made to run services between Brighton and Haywards Heath.
Services will still operate between London and Three Bridges.
