Delays of up to 40 minutes on Southern at Fratton due to electrical supply problems.
Disruption on Southern between Epsom and Horsham due to broken down train at Epsom. Tickets being accepted on South West Trains and First Great Western services.
Southern trains has announced an order of 116 new train carriages for its routes in Sussex and Surrey to help ease overcrowding.
They will be built in the UK by train manufacturer Bombardier at a cost of £180 million.
The order has the provision of an extra 140 carriages which can be called in the event that further investment opportunities are identified, bringing the potential total order value up to £385 million.
Managing Director Chris Burchell said: “We have worked extremely hard to be an effective delivery partner to the Department and we are very pleased to have reached this important milestone in the procurement of new rolling stock. This will provide essential capacity to allow our industry to grow.”
The Secretary of State for Transport, Patrick McLoughlin said: “Increasing the number of trains on the network not only benefits passengers but everyone, as the railways are an important engine for economic growth in our country.
“The Government has worked closely with Southern to enable this critical stage of the project to be reached and I look forward to these trains being delivered onto the network.”
Southeastern and Southern rail services are expected to face some disruption tomorrow, according to the train operators.
Southern is introducing a special timetable which means there will be fewer services on some routes.
Southeastern is today experiencing some snow related problems but all lines are running.
Tomorrow the company is planning to cancel a number of early morning services to enable longer trains to run which reduces the possibility of failures.
An army of Southeastern staff volunteers are out at stations in Kent and Sussex to try to clear them of ice and snow.
The company says many workers have turned up at stations to carry out the work in an attempt to reduce the risk of injury for passengers.
Full details will be on the companies' websites later.
South West Trains and First Great Western will be operating as many services as possible but passengers are advised to check later tonight for any potential problems.
Chiltern Railways says significant snowfall is expected over the next 24 hours.
A spokesman said: "We will be running our regular timetable, but there is a risk we may experience delays and short notice cancellations. Please check before travelling."
Advance Warning for Monday 21st January 2013 - No service on South West Trains between Ascot and Ash Vale, between Virginia Water and Weybridge, between Salisbury and Bristol Temple Meads and between Guildford and Leatherhead due to poor weather conditions.
All other routes are open, but there is no train service at Addlestone, Bagshot, Beaulieu Road, Camberley, Chertsey, Frimley, Longcross and Upper Halliford.
Delays of up to 20 minutes on Southern between Brighton and Victoria, and between Brighton and Portsmouth Harbour due to signalling problem at Brighton. Southern do not have an estimate for normal service. Also affecting First Capital Connect.