Rail operator Govia Thameslink is warning passengers that Thameslink, Gatewick Express and Southern services could see emergency speed restrictions in place tomorrow (Saturday) due to high winds.
Severe weather and winds of up to 60 mph are forecast from the start of the service, with delays expected.
GTR says the worst affected areas are expected to be south of Three Bridges and Hurst Green, and between Ashford International, Brighton and Barnham (East and West Coastway).
As a result, there will be no Gatwick Express service running between Gatwick Airport and Brighton until 14:30.
Trains between London Victoria and Eastbourne, and between London Victoria and Littlehampton will be reduced to an hourly service.
On its website, GTR addedL "High winds can cause a number of problems for the railway, in particular, obstructions caused by trees and other debris blown onto the lines. In exposed coastal areas where gusts are strongest, high waves may also cause damage to tracks and ballast (the small stones which tracks rest on).
"Network Rail will have additional staff in place ready to respond to potential problems. They also have specialist chainsaw trained teams ready to remove fallen trees and branches."
Passengers are advised to check before they travel tomorrow.
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