Current Surface Temperature of Lake Ouachita is 70 - 74 degrees. May 25th
Lake Ouachita Surface Temperature can vary about 4 degrees or more a day depending on condition effecting the lake.
When you talk water temperature variants you are discussing principles in limnology.
Time of day, weather (clouds, rain, wind speed and direction ) clarity of the water, sun exposure including the angle and duration of exposure, flow of water, whether warmer or cooler into lake, mixing of water column layers through wave or boat action, substrates they are in contact with (bottom, shoreline, plant growth), evaporation rate and location on lake all play a part in surface temperature.
Surface temps of water in mid summer may reach as high as 95 degrees, although the water 2 ft. deep could be significantly cooler.
Water maintains its temperature very well. The ability of water to retain dissolved oxygen is also related to temperature.
This is where you can get some errant data. If a cove was very calm and undisturbed as you entered it your temp sensor, you are only measuring the top surface temp. If there has been several days of high sun and dead wind the surface temps will raise significantly compared to the water just below.
In the winter the northeast side of coves that are relatively undisturbed on the north and east side of the lake that have the north shoreline protected by hills or trees will warm the fastest.