Superficial humidity can be measured even through a remote instrument. You can choose between two possibilities:
Infrared thermometer with humidity meter; it can measure the environmental air humidity and the difference compared to the dew point. In this way you will be able to recognize promptly where there’s the risk of mold growing and to take countermeasures.
Thermal imagers with humidity meter; they not only can measure the surface moisture, but they also make it more visible. This is really important to recognize where there’s danger of mold formation. The thermal image in fact makes it clear simply using traffic lights principle. Where there’s high risk of mold formation it is portrayed in red, where there’s low risk it’s portrayed in green. Yellow represents borderline points.