In my experience surface temps can be misleading. A few years back I had a temp probe on a long cord and it would always show the surface temp different from just a few feet down. A few warm days in winter with lots of sun would really warm up the surface but just a few feet down it was a differnet story. :)Depending on season, it might be cooler or warmer. It was an instant read so it also showed the thermal cline. I really miss having one. No one makes one anymore that I can find.