A hot tub is probably one of the most ideal places to relax after a long day at work or a grueling workout. And it’s also a pretty cool way to get some alone time or just hang out with some friends.
But nothing ruins the experience faster than a tub that’s too cold where your friends freeze their toes off. Or in water that’s too hot where you risk someone passing out.
Not to mention the effect a constantly overheated spa will have on your equipment and your electric bill!
While all of this probably makes sense to you, you might be wondering what the perfect temperature is and how you can keep it there.
No worries! You’re about to learn everything you ever wanted to know on the subject.
Why Does Hot Tub Temperature Matter?
Although everyone’s baseline is different, the average temp for the human body is 98.6℉. So the water must be at least hotter than that for us to get any physical sensation from it.
This heat is what dilates the blood vessels, pumping more oxygen through your bloodstream. And it’s what soothes aching muscles and relaxes your body.
However, it is possible to get your water too hot, and that’s when it can become hazardous. In fact, spending too long in even the correct hot temps can cause you to faint, become nauseous, and be at risk for heatstroke.
Additionally, keeping your water at the correct temperature is key in keeping bacteria and contaminants at bay, as well as protect your equipment. Water that’s too hot can be a breeding ground for all the icky stuff, but water that’s too cold can lead to frozen pipes in the winter.
Basics of Heating a Hot Tub
Assuming everything is in working order with your spa heater, all you need to do is turn it on and set it to your desired temperature.
Some spas are even designed to be compatible with smartphones so that you can control the heater from wherever you are. This is particularly handy if you want to get it heated up on your way home or if you think you might have forgotten to turn it off.
Once you’ve turned on the heater, you might have to wait a few hours for the water to heat up, but other than that, you’re all set.
Over time, things can go wrong with any mechanics and hot tub heaters are no exception. For this reason, it’s smart to also buy a stand-alone water thermometer to make sure your spa thermostat is always working correctly.
How To Find the Perfect Hot Tub Temperature
According to CDC guidelines, hot tub temperatures should never exceed 104℉. Because of this, most spas have a regulator that prevents them from going over that temp.
But just because that’s as high as your tub should go doesn’t necessarily mean you should always keep it there. Most people find 100-102℉ to be ideal, so we recommend you start on the low end of that and see what feels right.
In other words, finding the perfect spa temperature for you will depend mostly on what you consider comfortable but there are a few situations where this could change.
Winter Hot Tub Temperatures
If you’re not hot tubbing in the winter, it’s best to go ahead and drain it and winterize it. This way, you don’t have to worry about keeping it warm enough to avoid disaster.
On the other hand, if you do use your hot tub in the winter, you’ll want to keep the temps above freezing to keep the water freezing in the pipes and damaging your equipment.
You can set the temp a little above freezing at around 50°, but keep in mind that it will take a while to heat up to a usable temperature from there. If you use your hot tub often in the winter, you’ll probably want to keep it a little warmer than usual since the cool air will cool it down.
And always keep a cover on your tub while it’s not in use. This will keep the heat in and save some energy in the process.
Summer Hot Tub Temperatures
Summer hot tub temp preferences are different for everyone. Some people prefer to keep the water a little cooler — around 85° or so — for a more refreshing experience. This, of course, is entirely up to you.
Hot Tub Temperatures for Kids & Older Adults
Children and older adults are often a lot more sensitive to extreme temperatures than other people. So, if your bathers happen to fall into these categories, you’ll probably want to consider lowering the temperature to around 95°.
Also, be sure to limit the amount of time these groups of people spend in the hot tub. It’s recommended that children spend no more than 10-15 minutes in hot water, and older adults, no more than 20.
This is especially true for people with certain health conditions. Those with high blood pressure or heart disease should definitely speak to their doctors before enjoying a hot tub.
The same goes for pregnant women. They should lower the hot tub temperature to around 100° and stay in no more than 10 minutes at a time.
Tips for Maintaining Hot Tub Energy Efficiency
If you’re not careful, it’s easy to see sky-high electric bills when a hot tub is in use. But there are a few things you can do to make sure you’re not caught off-guard.
First of all, keeping the heater on a consistent temperature is the best way to keep it running efficiently.
If you choose instead to turn it down when it’s not in use and back up before you get in, you are forcing the equipment to work much harder than needed much more of the time. You’ll also see the results in your electric bill and you’ll decrease the life of your equipment.
Secondly, insulating your hot tub is a smart move for energy-efficiency. Just wrap the bottom of the tub under the surrounding with any insulation you wish.
Lastly, keep the cover on any time the tub is not in use. This will reduce heat loss and keep your heater from working overtime.
Low Hot Tub Temperature: Pros & Cons
When we talk about low hot tub temps, we aren’t talking about temps so low, they’ll cause hypothermia.
No, we are talking about a water temperature barely above or below the normal body temperature that is just comfortable enough not to make you squirm. Some people like this and others want their water as hot as they can get it.
Pros of Low Hot Tub Temperatures
Safer for kids
Safer for adults
Safer for pregnant women
Refreshing on hot summer days
Costs less to heat
Less wear and tear on your equipment
Cons of Low Hot Tub Temperatures
Risk of freezing in winter months
Takes longer to heat the water when you do want it warm
Not as effective on sore muscles
Hot Tub Temperature FAQs
Is 105 or 110 too hot for a hot tub?
Most hot tub heaters won’t even let you set them that high because 104 degrees is the maximum temperature recommended by the CDC. This is because anything higher than that becomes a health hazard.
And don’t kid yourself into thinking these are loose guidelines. Water at 106℉ is enough to cause a heat stroke. And anything over 102 is very unsafe for pregnant women or people with health concerns.
What temperature should a hot tub be set at in the winter?
This depends on personal preference, but if you normally keep your hot tub on the colder side, you’ll definitely want to warm it up a bit during colder months.
This is because the cold air can steal some of the warmth pretty quickly. And the lower the temp, the shorter the distance to freezing, which can damage your pipes.
How long can you stay in a hot tub at 100 degrees?
At 100℉, the water is safe enough to stay in for up to 30 minutes or a little longer as long as you are a healthy adult. Just be sure to get out if you start to feel light-headed or nauseous.
There isn’t really just one perfect temperature for hot tubs. What you decide to set yours at depends on a lot of different factors.
The key is to take into consideration the age and any health concerns of your regular bathers. And then use common sense to determine the appropriate amount of time to stay in.
Hi, I’m Matt Harper, the founder of poolcareguy.com, a site I started with one simple mission: to help people around the world clean and take care of their pools and hot tubs on their own, without the hassle.
I’m not a professional pool cleaner and don’t have any formal training, I’m just an average guy who loves hanging out by his pool and hot tub and taking care of it. After many years on the job, I’ve become quite good at it.
On this website I will be teaching you absolutely everything I know about pools and hot tubs.