Travellers are being urged to take extra care as temperatures are expected to plunge, bringing icy conditions across the south.
The Met Office has issued yellow warnings of ice this week predicting temperatures well below zero.
SouthWestern Railway said: “Due to the recent forecast for cold and wet weather, poor rail conditions including ice are expected across the South Western Railway network throughout this week.
“Network Rail run special vehicles treat our tracks to reduce the effects of the poor weather conditions and will be taking appropriate action over the next few days”
Southwestern Railway is advising customers to check their journey before travelling.