Trains have been cancelled and delayed between London Waterloo and Barnes, causing issues for commuters in Richmond, Twickenham and Kingston areas.
A signalling problem at Clapham Junction, caused by a lightning strike, means some services are cancelled while others are delayed for up to 30 minutes.
Trains between Waterloo and Twickenham may terminate at Kingston.
Services to Richmond via the Hounslow loop have been cancelled.
Waterloo to Guildford trains are running non-stop to Surbiton.