Northwood Sauna Thermometer and Hygrometer 2 in 1, Fahrenheit & Celsius, Canadian Red Cedar

When you host, the gauge is not only for you. Guests who are new to sauna like to see a number, and a guided round changes the room quickly: every ladle pushes the humidity up and makes the same temperature feel hotter. This Northwood gauge splits the two readings across two dials in one red cedar frame – a thermometer with Fahrenheit on the outer ring and Celsius on the inner one, and a hygrometer for relative humidity.

Both dials are mechanical, driven by a metal spiral, so there is no battery to fail in the heat. The maker says they are calibrated at assembly and can be recalibrated with the included instructions. The listing gives no accuracy tolerance, and its detail table and the printed dial disagree slightly on the range, so read it as a guide rather than a lab instrument. The frame is 9.8 in (25 cm) long.

Tip: Hang it where guests can see it from the bench – at about head height for someone seated on the upper level, away from the heater and the door – and glance at the humidity dial after each pour.