Severe ice on rail tracks has caused severe disruption with passengers advised to travel only if absolutely necessary.
There have been major delays to South West trains services in and out of London Waterloo, with the services to Reading delayed by up to 90 minutes.
Some services may also be cancelled or amended at short notice.
Jake Kelly, customer service director for South West Trains, said: "We would like to apologise to passengers for the inconvenience this will undoubtedly cause them.
"We have extra stuff at our key stations to assist customers and provide information and we are keeping passengers on board our services updated as best we can by keeping in close contact with our train brands.
"Anyone who chooses to travel should check for service updates before leaving for the station.
South West Trains will be publishing compensation arrangements for customers shortly
Visit www.southwesttrains.co.uk for more information.
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