South Wales Police says the A465 is closed between Aberdulais and Resolven, after a serious crash.
Diversions are in place via the B4242.
More top news
It will be a dry night with clear spells for all of us, but the south-easterly wind will increase, becoming rather windy by morning.
Hundreds of campaigners are marching through the streets of Cardiff calling for the city's grassroots music venues to be protected.
People in Wales living with cancer face losing over £500 a month in income after diagnosis, according to Macmillan Wales.