South Wales Police says the A465 is closed between Aberdulais and Resolven, after a serious crash.
Diversions are in place via the B4242.
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Some bright spells this afternoon, with outbreaks of rain. Top temperature 15°C.
It's judgement day at the Millennium Stadium as Cardiff Blues take on the Ospreys and the Newport Gwent Dragons face the Scarlets.
Showers expected throughout the day especially in the north. Drier and brighter elsewhere but cooler than in recent days.