Services to and Watford Junction look set to be delayed or cancelled throughout the day due to flooding.
Yesterday evening, parts of London were hit by torrential rain leaving several streets in the capital underwater.
Railways lines were also affected including the West Coast mainline out of London Euston.
The line between Euston and Watford was completely shut yesterday evening to allow engineers to assess and clear the flooding in north London.
The situation has improved this morning but issues on the line have persisted and according to the Trainline app, a number of services between Watford and Euston have been cancelled throughout the day, which will also affect stations including Bushey and Kings Langley.
The majority of services are running to schedule.
National Rail's website states this morning: "Yesterday, heavy rain flooded the railway lines at London Euston. Consequently, trains were unable to run to/from the station.
"However, lines between London Euston and Watford Junction have now reopened for Avanti West Coast, Caledonian Sleeper and London Northwestern Railway services.
"Avanti West Coast and London Northwestern Railway trains to and from London Euston may be subject to short notice cancellations or delays of up to 30 minutes."
National Rail adds London Overground services are still unable to run between London Euston and Kilburn High Road due to essential repairs following the flooding.
It means there are severe delays on the Overground line between Kilburn High Road and Watford Junction.
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