At a glance
- Usual temperature: 37–40 °C.
- Heating time with wood: usually 1.5 to 3 hours.
- A floating thermometer is essential: your hand is a poor judge.
The right temperature
| Temperature | How it feels |
|---|---|
| 35–37 °C | Gentle, for long soaks, children (under supervision) or summer |
| 37–39 °C | Comfortable for most adults |
| 39–40 °C | Very hot, best for winter and shorter soaks |
Measuring properly
Hot water rises: the surface can be much hotter than the bottom, especially with an internal stove. Stir the water with a paddle or a stick before measuring, then use a floating thermometer.
Cutting heating time
- Keep the lid on while heating.
- Burn dry wood.
- Fill with water that is as warm as possible.
- For frequent use, consider a hybrid model that keeps the water hot.
Precautions
- Stay hydrated and avoid alcohol while bathing.
- Take breaks and get out if you feel faint or dizzy.
- Always supervise children and check the temperature before they get in.
- Pregnant women and people with heart or blood pressure conditions: ask a doctor for advice.
- Do not touch the stove or the flue, which get extremely hot.
Sources and method
Figures checked on 4 November 2026. Prices taken from the makers’ public product pages; rules and data from the official sources below.
- HSG282 – The control of legionella and other infectious agents in spa-pool systems — Health and Safety Executive (UK) : typical spa-pool operating temperature is 30–40 °C; warm water may pose a risk to users who are pregnant or have cardiovascular problems
Frequently asked questions
How long should you stay in a wood-fired hot tub?
There is no single rule: listen to your body and take breaks, especially above 38 °C. Stay hydrated and get out as soon as you feel unwell, dizzy or overheated.
Are hot tubs unsuitable for some people?
Hot baths may be inadvisable for pregnant women, young children and people with cardiovascular conditions or blood pressure problems. If in doubt, ask your doctor.