Why Do People Wear Hats in the Sauna?
People wear a hat in the sauna because the air at head height is hotter than the air around the rest of the body, and sauna air is very dry. A wool sauna hat keeps a layer of cooler air around your head so the heat feels less intense. Redwood Outdoors recommends judging each session by how you feel, not by the hat.
Key takeaways
- Hot air rises inside a sauna. In a traditional Finnish sauna, the air near your head can reach 176°F to 212°F (UL-listed saunas in the US top out at 194°F), while the air near your feet is noticeably cooler.
- Sauna air is dry: relative humidity in a traditional sauna usually runs 10% to 20%.
- A sauna hat changes how the heat feels on your head. It does not lower your core temperature, so the signals that tell you to step out stay the same.
- A sauna hat only works when it is dry. A soaked hat loses most of its insulating ability.
- Redwood Outdoors sauna hats are made from merino wool, a natural fiber that performs well in high heat.
If you have ever watched someone step into a sauna wearing a hat like that and thought what's with the hat?, you are in good company. Redwood Outdoors customers ask about it all the time, and the answer starts with how heat behaves inside a sauna.
Why do people wear a hat in the sauna?
People wear a sauna hat because your head takes more heat than the rest of your body. Hot air rises, so the air near the ceiling of a traditional Finnish sauna can reach 176°F to 212°F while the floor stays noticeably cooler. In the US, UL-listed saunas are capped at 194°F. When you sit down, your head is the highest part of your body, so it gets the hottest air while your feet stay in the cooler layer near the floor.
A 2018 review in (Mayo Clinic Proceedings, 2018) puts the relative humidity of a typical sauna at just 10% to 20%. That combination, hot and dry, is what your head registers first.
A sauna hat slows down how fast the heat reaches your scalp, so your head stays comfortable even as the rest of your body warms up.
Does a sauna hat let you stay in the sauna longer?
A sauna hat makes the heat at head level more comfortable. It does not change how your body handles heat, and Redwood Outdoors does not recommend treating a hat as permission to sit longer.
A 2025 meta-analysis in the (International Journal of Sports Physiology and Performance, 2025) (Stevens et al., 63 studies, 618 participants) found that cooling the head, face and neck reliably improved how hot people felt, while the effects on core temperature were negligible. Your head tells you how hot you feel, but it is not where your body regulates its temperature.
A 2011 Massey University study in (Physiology & Behavior, 2011) (Schlader, Simmons, Stannard and Mündel) confirmed this: subjects in heat had their faces physically cooled or treated with menthol, which only changes the sensation of temperature. Both drove the same behavioral shift while heart rate, core temperature and sweat rate stayed identical.
A more comfortable head is worth having, but the same session timing still applies. Redwood Outdoors recommends the same practice with a hat as without: 10 to 20 minutes per round, two or three rounds with cool-downs, and out whenever you feel lightheaded.
Why are sauna hats made of merino wool?
Merino wool works well in a sauna because it blocks heat, handles sweat without feeling wet, and holds up over time. The fiber is naturally crimped, which creates tiny pockets of air that slow heat transfer. It absorbs moisture without feeling wet, and it resists the odor that builds up when any fabric gets sweated in repeatedly.
That is why Redwood Outdoors uses merino for both the traditional felt sauna hat (thicker, structured, with a zigzag edge, in green, grey or cream) and the Sauna Beanie (lighter, 100% merino from New Zealand, microplastic-free, in two lengths one inch apart).
When should you wear a sauna hat, and when should you take it off?
Keep a sauna hat on in the heat and off everywhere else. Keeping it dry between rounds is the whole trick.
| Moment in the session | Sauna hat | Why |
|---|---|---|
| First round | On, dry | Your head is in the hottest layer of air; the hat keeps it comfortable |
| Throwing water on the stones | On, out of the splash | Löyly sends a burst of humid heat upward; keep the hat dry |
| Cool-down, shower or fresh air | Off | Let both your body and the hat cool and dry before the next round |
| Cold plunge | Off | Water soaks the wool and removes its ability to insulate |
| Second and third rounds | Back on, if still dry | A dry hat works just as well on round two; a damp one does not |
| Any lightheadedness | Off, and step out | Listen to your body; the hat does not change when it is time to stop |
Some people soak their hat before a round, but that works against the thing you bought the hat for. Research published in the (Journal of Natural Fibers, 2019) (Akcagun, Bogusławska-Bączek and Hes) found wool thermal conductivity rose more than threefold as moisture increased, so a wet hat loses most of its insulating ability.
Does a sauna hat protect your hair?
Yes, a sauna hat shields your hair from the dry air inside the sauna, helping it hold onto moisture. Sauna air runs just 10% to 20% relative humidity, which pulls moisture from hair and scalp much like a desert climate. The hat keeps the driest, hottest air off your head, so your hair comes out of a session less parched.
Worth knowing: research published in (Annals of Dermatology, 2011) (Lee et al.) found that permanent keratin damage begins at around 284°F. A traditional sauna stays at 176°F to 212°F in Finnish practice, and UL-listed saunas in the US are capped at 194°F, well below that line. So even without a hat, the dryness from a sauna session is temporary and reversible once your hair rehydrates.
Why is a sauna hat sometimes called a banya hat?
The thick felt hat comes from Russian banya bathing culture, where it is close to standard equipment, which is why "banya hat" and "sauna hat" often name the same object. Redwood Outdoors uses "sauna hat" for consistency. In Finnish tradition, bench height, ventilation and unhurried cool-downs do the same job, making the hat one option among several.
A few things to keep in mind about sauna sessions
Whether you wear a hat or not, a sauna hat does not change how your body responds to heat, so the basics of a good session stay the same. Stay hydrated, keep rounds to 10 to 20 minutes, and step out whenever your body tells you to. If you are pregnant or postpartum, managing a cardiovascular condition, or taking medications that affect blood pressure, check with your physician before making sauna bathing a regular habit.
For families: children can enjoy a sauna at a lower temperature and a shorter duration, with an adult present. A hat can make them more comfortable, but it is not a reason to extend their time.
FAQs
What happens if you don't wear a sauna hat?
Nothing wrong with that. You feel the heat on your scalp sooner, and your hair sits in 10% to 20% relative humidity air. Many people bathe without one their whole lives and simply prefer a lower bench.
Can I wear a baseball cap or a regular beanie instead?
Avoid caps with plastic or metal parts because they get uncomfortably hot against the skin. A merino wool sauna hat is the best option for dry heat.
How do you wash a merino wool sauna hat?
The Redwood Outdoors Sauna Beanie is machine washable on cold and hung to dry. A traditional felt sauna hat is hand washed with wool detergent and laid flat. Skip the dryer, and never dry either one on the heater.
Should you wear a sauna hat in a cold plunge?
No. A wet hat loses most of its insulating value. Leave it somewhere dry and put it back on when you return to the heat.
The hat is a small thing that regulars end up caring about a lot. The Redwood Outdoors team is happy to talk through the rest of it too: benches, heaters, where the hook goes by the door. Visit us at our showrooms in Seattle, Los Angeles or Salt Lake City to see our full sauna and accessory lineup in person.
Sources
[1] Laukkanen JA, Laukkanen T, Kunutsor SK. Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings, 2018;93(8):1111–1121.
[2] Stevens CJ, Borg D, Brade C, et al. Head, face, and neck cooling for performance: a systematic review and meta-analysis. International Journal of Sports Physiology and Performance, 2025;20(6):743–763.
[3] Schlader ZJ, Simmons SE, Stannard SR, Mündel T. The independent roles of temperature and thermal perception in the control of human thermoregulatory behavior. Physiology & Behavior, 2011;103(2):217–224.
[4] Lee Y, Kim Y-D, Hyun P-I, et al. Hair shaft damage from heat and drying time of hair dryer. Annals of Dermatology, 2011;23(4):455–462.
[5] Akcagun E, Bogusławska-Bączek M, Hes L. Thermal insulation and thermal contact properties of wool and wool/PES fabrics in wet state. Journal of Natural Fibers, 2019;16(2):199–208.