There is disruption on Arriva Trains Wales between Abercynon South and Merthyr Tydfil due to flooding at Merthyr Vale.
The company says all lines are currently blocked and it does not have an estimate for when a normal service will resume.
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ITV Cymru Wales will publish the final poll of the Welsh Assembly Election 2016 campaign on Wednesday this week.
A mostly cloudy day with outbreaks of light rain and drizzle at times, mainly over the mountains where it could occasionally turn heavy.
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