A lightning strike is causing train disruption between Holyhead and Bangor.
Signals have been damaged at Holyhead, meaning a replacement bus service is running instead.
There is no estimate for when a normal service will resume.
Train users returning to work today have seen another rise in the cost of tickets, with an average increase of three per cent across train fares.
It's the smallest hike in four years, but that's little comfort to commuters - who say their wages aren't rising and are struggling to pay the increase. Lorna Prichard reports.
John Rogers, of Rail Future Cymru, told ITV News that the UK has some of the highest rail fares in Europe and the Welsh Government's intervention, in lowering the increase, was small compensation. He said that high rail fares are a deterrent for people using the trains.
Train companies retain an average of just 3p from every pound paid for rail tickets, with the vast majority of revenue going on maintenance, staff costs and investment in the rail network, according to figures released by the industry association the Rail Delivery Group:
Rail fares are to go up by an average of 3.1% today. Despite the increase, it's the smallest rise in four years.
This means ticket prices such as an open return from Newport to Swansea, will go up from £16.00 to £16.50.
Last week, the Welsh Transport Minister announced season ticket prices will be held below the rate of inflation in an attempt to encourage the use of public transport.
A discounted multi-ticket system to enable more flexible travel at a lower price, which will benefit part- time workers will also be introduced.
But Welsh charity Sustrans Cymru say they are concerned that many people will be affected by the increase as salaries have not gone up.
Arriva Trains Wales has suspended its service between Trehafod and Pontypridd due to flooding.
With many people expected to travel to share Christmas with family and friends, National Rail Enquires said that very strong winds and heavy rain are forecast throughout England, Wales and Scotland on Monday December 23.
"This may mean that some trains are delayed or cancelled, and some train operators may run an amended timetable," it said in a statement
The train operation companies that could be hit include:
Arriva Trains Wales; c2c; Chiltern Railways; CrossCountry; East Coast; East Midlands Trains; First Capital Connect; First Great Western; First Hull Trains; First TransPennine Express; Gatwick Express; Grand Central; Greater Anglia; Heathrow Connect; Heathrow Express; Island Line; London Midland;
London Overground; Merseyrail; Northern Rail; ScotRail; South West Trains; Southeastern; Southern; Stansted Express; Virgin Trains.
For the latest update check the National Rail service alteration page.
Commuters who travel by train in Wales are putting up with a service that's lagging behind the rest of the UK.
That's the verdict of a report by Campaign for Better Transport. They say there are problems with access and low satisfaction with the services on offer.
The report argues a more joined up approach is needed along with the devolution of more responsibilities to the Welsh Government.
Our Political Reporter Owain Philips has the story.
Network Rail and Arrive Trains Wales will invest over £1m to the programme and hope it will encourage more people to use train services.
Mike Bagshaw, Commercial Director of Arriva Trains Wales said:
"We are very excited about these improvements and are pleased to be involved in programmes that support a safe, accessible and sustainable transport network across Wales.
"Our investment in this series of projects will build on the £30 million Arriva Trains Wales has invested over the last 10 years to improve stations, staff facilities and training, service availability and ticket purchase opportunities."
Mark Langman, Route Managing Director of Network Rail said:
"The aim of the scheme is to revitalise the station environments by making noticeable and lasting improvements for the benefit of passengers.
"Stations are the shop window for the railway and we hope this improvement programme will encourage even more people on to the trains at a time when we are seeing record passenger numbers."
Speaking at Port Talbot Parkway station this morning, where work will begin next week, Transport Minister Edwina Hart told ITV News today's investment will help improve passenger experience and encourage the use of public transport.