87 is pretty hot, but water movement or lack of will change the temps drastically.
Heck it was blowing coming out of the ditch this morning with 1-2' swell, on way back it the wind fell out as did the swell....weird thing is never seen the water have a slight ripple then down middle of it slick calm but like it was it's own entity. But what causes this? Yesterday and all the previous week it was 70-73.