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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Staying mostly dry overnight with generally light winds, but cloud and wind will gradually increase from the northwest from the early hours.
In the last programme we've been to meet two Welsh entrepreneurs who chose a different route and we visit the Energy Centre at Coleg Menai.
ITV news presenter Jonathan Hill reflects on this week's Wales at Six special series on Welsh education.