High water levels have led to the closure of Dyfi Bridge.
The closure is expected to affect travel for some time.
Lloyds Coaches say some of their services will be affected. A spokesperson for the travel company said: "Service T2 will divert between Dolgellau and Machynlleth via Dinas Mawddwy and [is] unable to serve Corris.
"Service X29,34 will divert via Llanwrin and be subject to lengthy delays and possibly cancellation.
"Apologies for inconvenience caused."
We will bring you more news as we get it.