OK, I understand that bass come to shallower waters in summer; they like warm water. But, why would they then go to deeper waters in the winter. Isn’t the deeper waters the coldest?

Bass like warmer water and feed more in warm water temperatures. In colder water, bass will eat less and not be as active. Bass are warm-blooded and are more active in warm water. The season has nothing to do with were or how the bass feeds or are located, it is the water temperature. Bass do not migrate to other areas of the river or lake like other fish do, they will move a short distance away to different water temperatures. The reason bass move to warmer shallow waters for spawning is because the eggs need light and warm waters. They will stay in shallow waters until the hot summer sun starts to warm the water into the seventies and eighties. After this happens, the bass will move to the deeper waters were the temperature is cooler. They do not like extreme water temperatures. When the waters cool down in shallow waters during the fall, they come back. The reason they go deeper during summer and winter is that there are no temperature fluctuations and the water is more stable. It is not so much that bass go deeper as much as they move a short distance to avoid the unstable water conditions in the shallow waters. They need stable oxygen levels to stay alive and deeper waters provide this stabilization. Even if you think they are going deeper, they may only be in fifty feet of water, which is still shallower than what some other fish will go when winter comes.