You can wear the sensor in the sauna, but we do not recommend it, as the sensor can fall off more easily when your skin is sweaty. The temperature range specified by the manufacturer is between 10 °C and 45 °C. 

A sensor that has fallen off after a sauna session cannot be replaced free of charge.

Please note that no measurements may be recorded as the sensor may switch itself off if the temperature is too high. However, it will switch back on when the temperature returns to normal. You may also see an incorrect peak value during a sauna session.