I've always been under the impression that the colder water would be more oxygenated. I didn't realize in the summer below the thermocline becomes a "dead zone". Like you, I mainly fish the spring and fall because I don't like the heat of the day, nor do I like dealing with jet skis and ski boats all day. I'm planning on going to Jordan, or Harris Friday afternoon/night. I'll definitely be keeping an eye out for the thermocline now.