Flooding in the South Croydon area has forced Gatwick Express to reduce the number of trains it can operate.
Trains today (August 2) are operating every half hour. They usually depart every 15 minutes.
From London Victoria to Gatwick services are departing on the hour and 30 minutes past the hour.
From Gatwick Airport to London Victoria, trains are leaving at 20 and 50 minutes past the hour.
A burst water main and landslip have been blamed for the disruption.
The rail operator has not confirmed when it expects to be able to resume normal operations.