Cheap pool thermometers do just fine as shorty said. Surface temperatures are difficult to accurately get because the first several inches can vary greatly so, I take "surface" temps at 6 inches, then take a deeper reading at 18", then the bottom. That will tell you most of what you need to know. I have a dock which makes taking readings really easy. In the absence of a dock...a heavy fishing pole and big bobber would suffice. Just don't get it hung up or you'll lose your $5 investment. Lol


Fish on!,
Noel