Or just get a temp gauge/probe if you do not want the hassle of installation and price for a graph.

Within these larger, slower moving pools within rivers, some of that water is never forced downriver until the water gets high. This can mean weeks or months sometimes. Most of the current in these big pools are just in the top part of the water column and almost always exclusively very near the main channel of water coming in.

The next time you get high muddy water, pay attention to how the big pools clean up. The area near the channel cleans first then the outside edges slowly clean up via the sediment depositing in areas of reduced current. The stained/muddy stuff absorbs the radiant heat from the sun and will be warmer than the new water coming in by the main channel.

Clean vs. dirty and moving vs. stagnant water all impact temperature which directly impacts dissolved O2.