A dry sauna is a sauna with low humidity, which in practice means a traditional cabin with a heater and rocks that you are not pouring much water over, or an infrared cabin that adds no moisture at all. The word exists mainly to separate these from a steam room, where the air is saturated. It is a description of the air rather than a product category, which is why the same cabin can be a dry sauna on one session and a humid one on the next.
Dry, wet and steam are a humidity scale
A traditional Finnish cabin runs hot with low background humidity, and you raise the moisture in short bursts by ladling water onto the hot rocks. Used without water it is a dry sauna; used with water it is often called a wet sauna, though it is the same room and the same heater. An infrared cabin is dry by construction, because there are no rocks and no water involved. A steam room sits at the far end: much cooler air, saturated with moisture, which is why it feels hotter than the thermometer suggests.
Why dry heat feels different
Dry air lets sweat evaporate, and evaporation is how the body sheds heat, so a dry sauna at a high air temperature is tolerable in a way that the same temperature saturated with steam would not be. That is the whole reason a traditional cabin can run far hotter than a steam room. It also explains the common complaint that a dry sauna feels harsh on the nose and throat: there is very little moisture in the air you are breathing, which is part of why regular users ladle water over the rocks in bursts rather than sitting in fully dry heat throughout.
Choosing a dry sauna
If you want dry heat specifically, both a traditional cabin and an infrared cabin deliver it, and the choice between them comes down to temperature and installation rather than humidity. A traditional cabin reaches much higher air temperatures, needs a heater sized to the room, and above a certain size needs a dedicated circuit. An infrared cabin runs cooler, heats faster and often plugs into a normal outlet. Neither adds moisture unless you do, so both answer the phrase, at genuinely different prices and installation demands.
Questions people ask about dry sauna
What is the difference between a dry sauna and a steam room?
Humidity, and therefore temperature. A dry sauna runs hot with very little moisture in the air; a steam room runs far cooler but at full saturation, which is why it still feels intense.
Is an infrared sauna a dry sauna?
Yes. An infrared cabin has no rocks and no water, so it adds no humidity at all. It runs at a lower air temperature than a traditional cabin while still being dry heat.
Can you pour water in a dry sauna?
In a traditional cabin with a rock-filled heater, yes, and that is how the humidity is raised in bursts. In an infrared cabin you should not, because it has no rocks and is not built to take water.