Winter flounder are distributed from the coast of Newfoundland and Labrador in the north to Georgia in the south. Their range is limited to the western Atlantic. Winter flounder live on a variety of substrates: muddy, sandy or pebbled bottoms at fairly shallow depths (usually less than 100 metres). They have been known to venture into the brackish waters near rivers or estuaries.

Winter flounder are oval-shaped fish, strongly compressed and with a fairly straight lateral line leading to a rounded tail. They have a small mouth with few teeth (sometimes none at all). Their body colour varies according to that of the ocean floor. Usually winter flounders are brown, reddish-brown or olive green-nearly black in some cases-with a pale white underside. Sometimes they are mottled or speckled. On the eyed side, their scales are rough. They can grow to a length of 50 cm or more. They have an average lifespan of 11 years for males and 12 years for females.