South West Trains commuters face more disruption as engineering works at London Waterloo have overrun.
Services from the station had been expected to return to normal after a month of improvements.
National Rail say services across the whole South Western Railway network may be cancelled, delayed or revised.
Work to increase capacity on trains leaving Waterloo has caused weeks of cancellations and delays.
Other incidents including a train derailment have also affected services to and from the South West. National Rail say they hope to have all trains running as normal by midday.
South Western Railway are advising people to check before they travel.
You can find a full list of affected South West services on SWR's website.