From the FGW^▸ (First Great Western) website :

14:22 Portsmouth Harbour to Cardiff Central due 17:40
This train has been revised. It will additionally call at: Dunbridge, Dean and Dilton Marsh.

11:30 Cardiff Central to Portsmouth Harbour due 14:49
This train has been revised. It will additionally call at: Dean and Dunbridge.

10:30 Cardiff Central to Portsmouth Harbour due 13:49
This train has been revised. It will additionally call at: Bradford-On-Avon.

14:26 Southampton Central to Cardiff Central due 17:25
This train will be started from Westbury. It will no longer call at: Southampton Central, Romsey, Dunbridge, Dean, Salisbury, Warminster and Dilton Marsh. This is due to snow.

Passengers travelling from Southampton Central to Westbury should travel the 1510 service.

10:00 Cardiff Central to Southampton Central due 13:17
This train has been terminated at Bristol Temple Meads. It will no longer call at: Keynsham, Oldfield Park, Bath Spa, Freshford, Avoncliff, Bradford-On-Avon, Trowbridge, Westbury, Dilton Marsh, Warminster, Salisbury, Dean, Dunbridge, Romsey and Southampton Central. This is due to snow.

Passengers travelling from Bristol Temple Meads to Southampton Central should travel the 1122 service.

10:22 Portsmouth Harbour to Cardiff Central due 13:41
This train will be started from Southampton Central. It will no longer call at: Portsmouth Harbour, Portsmouth & Southsea, Fratton, Cosham and Fareham. This is due to snow.

Passengers travelling from Portsmouth Harbour to Southampton Central should travel the 1017 service.

08:57 Brighton to Cardiff Central due 13:27
This train will be started from Barnham. It will no longer call at: Brighton, Hove, Shoreham-By-Sea and Worthing. This is due to snow.

Passengers travelling from Brighton to Barnham are advised to travel on the 0930 service.