Rail passengers faced delays this morning (Wednesday November 21) along the Arun Valley after ice prevented trains getting electricity from the third rail between Barnham and Horsham.
Earlier today the 5.56am Bognor Regis to London Bridge service experienced trouble drawing power from the third rail in the Arundel area, and was unable to go any further.
The 5.28am Portsmouth Harbour to Horsham service also had trouble getting power in the area, and was unable to proceed beyond Amberley.
Both services were trapped.
Lines have been re-opened but disruption is expected until noon.
Southern says ice can cause significant issues on the rail network as they coat the electrical equipment, stopping power from getting to the trains.
In addition to this, falling icicles can cause obstructions and steel rails can even freeze together if they become too cold.
When this happens, signals stay red and trains are stopped.