Why do I sometimes get a different temperature reading off my temperature gauge than CoastWatch shows on the contour image map?
The satellite scans the top millimeter of the water temperature. Your temp gauge might be through the hull or down on your transom; several inches or a few feet below the surface. That explains some of the differences. Also, don’t forget that the afternoon CoastWatch images are going to display reflected and surface heat, so evening or early morning imagery will more likely be similar to what you find out on the lake using your temp gauge. And remember, CoastWatch gives you general insight on a fairly large scale. Don’t try to make it work right down to the resolution of your temperature gauge.
