Strong south winds on Lake Ontario will move the warm surface water deep causing an influx of cold deep water to line the shore. Seen it many times. 80 degree temps...shoreline water was up to 70.... 2 days later it's 50.Rg
Water is densest at 39 degreesThis is why ice floats.Water will stratify in “like” temps.The heavier batch of water sinks and pushes the deep water upward.This turnover is seen a few times in late summer.We used to match the salmon staging at the heads of the rivers with the 3rd turnover.
Surface temps don't matter . Surface temp can be 80 and 2 foot down it can be 70
It is true that water is most dense at around 39 degrees F. It's a surprising property of water. That is why under normal circumstances ice does not form on the bottom of a lake or pond first. Good thing, or else most plant life would die in northern waters. But ice floats because when water changes phase from liquid to solid it locks up into a crystalline structure that takes up more room than when in a liquid form, regardless of the temperature of the liquid water. (An ice cube floats in water that has always been warmer than 39 degrees.) The fact that water actually becomes more dense as it warms from 32 F to 39 F is an amazing property of water and not what one would expect. As water warms above 39 degrees F it does what one would expect and becomes less dense.
A local perch guide on facebook told me that the cooler water temp down low doesnt matter... 🤣🤣🤣🤣