Southern Railway warned customers that they should only travel if they have to today (Monday 12 December) after the snowfall.
The West Coastway route is blocked by a “proving service” – a train sent out to check the route – and by the train sent to rescue it.
Elsewhere, there are delays and disruption, with strike action due to start tomorrow. Union members are also due to strike on Wednesday, Friday and Saturday.
The train operator said: “Severe weather is causing major disruption across Gatwick Express, Southern and Thameslink networks.
“Services may be cancelled, delayed or revised. This is expected until 3pm. Short-notice delays will occur across the network.
“Only travel if absolutely essential this morning.”
Most Gatwick Express services have been cancelled, with Southern and Thameslink trains expected to serve Gatwick Airport. This could add to any delays, Southern said.
But passengers were warned that there was no service between Hove and Littlehampton and Barnham in West Sussex.
Southern said: “Do not travel in this area at the moment.
“One of our trains running as a ‘proving’ service (to check the route) came to a stand near Angmering with a loss of traction.
“A rescue train was sent and unfortunately, this unit is now struggling. The route is blocked.”
Southern said: “Subject to any weather issues causing disruption, your ticket is being accepted at no extra cost on these routes south of London.
“Southern and Thameslink services mutually, via any reasonable route, and on any Gatwick Express services which are still running.
“Stagecoach 700 buses between Brighton and Portsmouth
“Brighton and Hove Buses where running (please note these are also severely disrupted).”
Southern also said: “As Gatwick Express, Southern and Thameslink are experiencing very cold conditions, with ice and snow, please make sure you are wearing appropriate clothing and that you are prepared to wait for a service.
“Staff recommend you carry water or a hot drink. Platforms and other station surfaces may be slippery.”
Southern added: “Throughout yesterday and last night, the freezing weather has been disrupting trains across the rail network.
“The drop in temperature and snowfall has caused some problems with trains and the railway infrastructure.
“While Gatwick Express, Southern and Thameslink had intended to run trains as advertised, some services will be cancelled at short notice.
“Network Rail response teams are working hard to remove ice from the tracks. Specialist engineering trains are also running in order to treat the rails with de-icer fluid.
“Wherever trains are being affected, Gatwick Express, Southern and Thameslink will be monitoring each service closely and working hard to get everyone to their destinations safely.
“Check before you travel. You can check your journey using the National Rail Inquiries real-time journey planner.
“You may be entitled to compensation if you experience a delay in completing your journey today.
“Please keep your train ticket and make a note of your journey, as both will be required to support any claim.”
People also need to be aware that most taxi drivers WILL NOT carry wheelchair-disabled people, even in cases where the taxi is pre-booked and seemingly confirmed.
On Saturday I spent more than FIVE HOURS at Brighton station while the station staff did everything they could to find a replacement for a pre-booked taxi that failed to arrive.
We saw dozens of Brighton taxis perfectly capable of taking me, and I was both able and willing to pay (again) to complete my journey, but the drivers made feeble excuses or simply refused without giving a reason.
My disability is purely physical. I don’t make wild animal noises or wave my arms around. I’m perfectly rational and easy-going. I just can’t walk very far.
”My disability is purely physical. I don’t make wild animal noises or wave my arms around. I’m perfectly rational and easy-going”.
Making will animal noises and waving your arms around is not a sign of irrationality or an excuse to be used not to be accepted into a cab.
I realise that, Nathan, and I sympathise with people who ARE afflicted in that way, but the point I was trying to make was that there’s nothing about me that might frighten a taxi driver. They just don’t like carrying people who aren’t fully mobile, and it’s long past time something was done about it.