The study aims to inter-compare infra-red satellite products of surface temperature over Bodensee/Lake Constance with Fiducial Reference Measurements (FRM) from thermal infrared field radiometers. The inter-comparison will enhance our understanding of satellite derived Lake Water Surface Temperature (LWST) observations and measurements with shipborne infrared radiometers (Heitronics KT15.85 IIP and ISAR). It will allow the validation of satellite-retrieved Surface Temperature products, in particular from Sentinel-3, as well as verifying the accuracy of KIT’s in-situ LWST. Furthermore, the study is expected to improve our understanding of per pixel uncertainty estimation models.