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Get My Free PlanSetting the right temperature for your hot tub in winter protects your equipment from freeze damage and saves energy. The ideal temperature depends on how often you use your spa and how cold it gets outside.
If you use your hot tub daily, keep the water temperature between 98°F and 102°F (37°C and 39°C). It takes more energy to heat the water if you use it every day.
If you use your hot tub only once or twice a week, keep the temperature set to at least 80°F (27°C) and increase the heat a few hours before using it. In freezing weather, keep your water heated and circulating, even if you’re not using it, to prevent freeze damage
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Your hot tub temperature should match how often you plan to soak. The more you use your spa, the warmer you’ll want to keep it. Most hot tubs won’t allow you to set temperatures above 104°F (40°C). This safety limit prevents overheating and protects users from heat-related injuries.
Keep water between 98°F and 102°F (37°C and 39°C). It takes more energy to heat your water than to keep it constantly warm. You can lower the temperature by 2°F (1°C) to save up to 10 percent in energy costs while still keeping the water relatively warm.
Set your hot tub to at least 80°F (27°C) if you use it only once or twice a week, and then heat the water a few hours before using your spa.. Maintaining a constant warm temperature uses less energy than repeatedly heating cold water. Your heater works harder bringing water from 50°F to 100°F than maintaining 80°F continuously.
Set your temperature to 80°F (27°C) if you’ll be away from the hot tub, or it’s freezing outside. Make sure your freeze protection setting is working if your spa has one. This automatically circulates water when temperatures approach freezing, even if you’re not home to monitor it.
If your hot tub will sit unused for more than four weeks, it’s best to winterize it. Check out our step-by-step guide on How to Winterize Your Hot Tub for more help.
The heating process takes longer in cold weather, and several factors affect heating speed: spa size, heater efficiency, outside temperature, and insulation all impact how long it takes to heat your water. Most hot tubs heat up at 3°F to 6°F (1.5°C to 3°C) per hour.
Your hot tub will take four to twelve hours to heat from lukewarm to soaking temperature in winter. Colder outside temperatures slow the heating process. Keeping your temperature set to 80°F (27°C) rather than completely cold water reduces heating time significantly (and ultimately saves you energy). Check out our guide on The Cost of Running a Hot Tub in Winter.
Running your jets doesn’t speed up your hot tub’s heating process. The jets move water through the system quickly, but heating speed depends on your heater’s power output and the outside temperature. Keeping your cover on and running the pump on low speed will help heat the hot tub faster by circulating the water and preventing heat from escaping.
Here’s how to use less energy to keep your hot tub warm in the winter:
Yes, leave your hot tub on overnight in winter. Your hot tub is designed to stay on and running. Maintaining a steady temperature overnight costs less than reheating cold water the next day and protects it from freeze damage in the winter. Your spa only needs minimal electricity to maintain the temperature once the water is heated, and the cover will help retain the heat.
Not only is setting the right temperature important for your comfort, but it also protects your equipment from freeze damage. Here are important temperature ranges to know:
Water at 104°F (40°C) is the maximum safe limit for hot tub use. Most hot tubs won’t allow you to set temperatures above this point. Using the hot tub for long periods at this temperature can cause overheating.
Water at 86°F (30°C) feels lukewarm rather than hot. While this temperature protects your equipment from freezing, it’s too cool for most people to enjoy soaking. You’ll likely find yourself uncomfortable in water below 95°F (35°C).
Yes, 90°F (32°C) is too cold for comfortable soaking. This temperature feels cool to the touch and won’t provide the relaxation benefits of hot water. Most hot tub users prefer temperatures at least 8°F to 10°F warmer than this.
Hot tub pipes freeze at 32°F (0°C), especially when water stops circulating. When stagnant water in your plumbing freezes and expands, it can split pipes and damage your pump and heater. Keep your water heated and circulating continuously when outside temperatures drop below freezing. For more help protecting your pipes from freezing temperatures, check out our guide on How to Keep Your Hot Tub from Freezing.
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Matt is the founder of Swim University. He's been in the pool and spa industry since 1996. His mission is to make pool and hot tub care easy. Each year, he continues to help people with water chemistry, cleaning, troubleshooting, and more.
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