defull Stainless Steel Sauna Hygrometer Thermometer with Color-Coded Dial, 5 in

A sauna without a gauge is guesswork: the same room can feel mild at 150 °F (65 °C) with dry air and fierce a minute after water goes on the stones. This defull gauge puts both readings on one 5 in (12.7 cm) dial – temperature from 70 to 250 °F (21–121 °C) on the upper arc, relative humidity from 0 to 100% on the lower one.

The dial is color-coded: per the listing, a red band covers 150–212 °F (66–100 °C), the range most traditional sessions sit in, and a green band marks 0–20% humidity, the dry starting point before any löyly. It reads in Fahrenheit only, and the listing gives neither an accuracy tolerance nor mounting details, so treat it as a guide rather than a lab instrument.

Tip: Hang it at about head height for someone seated on the upper bench, on a wall away from the heater and the door – right above the heater it will always read too high.