What’s A Normal Skin Temperature? + Why you Should Track It

Learn why your skin temperature may be fluctuating throughout the day.

If you wear a fitness tracker or sleep tracker such as a Fitbit, WHOOP, or the Oura Ring, you may have noticed that one of the biometrics that is provided by the fitness wearable is your skin temperature.

Skin temperature is a little different from body temperature that we are more accustomed to measuring via a thermometer, so many people are not sure what a good or normal skin temperature is and the potential benefits of tracking it.

According to WHOOP, the normal range for skin temperature measured at the wrist for healthy adults is between 33 and 37°C.

In this guide, we will discuss why measuring skin temperature can be helpful, factors that affect average skin temperature, and what is considered a normal skin temperature.

Let’s dive in! 

A person with their hands on their cheeks checking their skin temperature.

What Is Skin Temperature?

As the term describes, skin temperature refers to the temperature—or amount of heat—measured on the outermost surface of your body—your skin.

Your skin temperature is often significantly cooler than your core body temperature, particularly if your skin is exposed to cold and when measuring skin temperature on the extremities such as your toes or fingers.

Skin temperature is also prone to fluctuations based on your environment.

For example, if you are wearing the Oura Ring tracker and you wash your hands in super hot water, or are you soaking in a hot tub while wearing a WHOOP strap or FitBit, your instantaneous skin temperature reading would be much higher than if you are swimming in a cold pool or taking a walk outside in the winter.

While these acute changes in skin temperature are clearly reflective of the environment and don’t provide much information in terms of your health, changes in daily skin temperature or changes in your average skin temperature over time can be signs of illness and injury.

Additionally, for menstruating women, changes in daily skin temperature readings can be used to help track hormonal fluctuations with the menstrual cycle and potentially even help predict the onset of your period or when you are ovulating.1Baker, F. C., Siboza, F., & Fuller, A. (2020). Temperature regulation in women: Effects of the menstrual cycle. Temperature7(3), 1–37. https://doi.org/10.1080/23328940.2020.1735927

A thermometer that reads 37 degrees.

What is Normal Skin Temperature for Adults?

According to WHOOP, normal skin temperature for healthy adults measured at the wrist ranges between 33 and 37°C (92.3 and 98.4°F).2What is Skin Temperature and Why Should You Monitor It? (2021, September 29). WHOOP. https://www.whoop.com/us/en/thelocker/what-is-skin-temperature-and-why-should-you-monitor-it/

Therefore, when comparing core temperature taken with a thermometer versus skin temperature, normal skin temperature is almost always lower than average core temperature, typically said to be 98.6 degrees fahrenheit or about 37°C.

Furthermore, while average body temperature tends to be more stable, according to Polar, skin temperature naturally fluctuates up to one degree Celsius (1.8°F) from night to night.3Polar Technologies | Nightly Skin Temperature | Polar Global. (n.d.). Www.polar.com. Retrieved January 1, 2024, from https://www.polar.com/en/explore/skin-temperature

‌As mentioned, menstruating women will also notice changes in daily skin temperature at different points in the menstrual cycle.

During the follicular phase of the menstrual cycle, which is between menstruation and ovulation, body temperature is lower. As progesterone levels rise during the luteal phase (between ovulation and the next menses), so does body temperature.

You will see these changes reflected in morning skin temperature readings. 

A person shielding the sun from his eyes with a towel.

Why Does My Skin Temperature Change?

One important thing to note is that measuring or tracking your skin temperature can be valuable for health reasons because skin temperature plays a key role in helping your body regulate internal temperature.

We tend to think of the skin as nothing more than the external layer of the body, but the skin is actually the largest organ, making up approximately 15% of your total weight.4National Geographic. (2017, January 18). Skin and How It Functions. Science. https://www.nationalgeographic.com/science/article/skin-1

‌Additionally, because of the thickness of the skin and the underlying fat tissue and how well perfused different areas of the skin are with blood vessels, there are rather significant regional variations in skin temperature across different parts of your body.

In general, the extremities, such as the fingers and toes, have the coldest average skin temperature.

This is particularly true in situations where someone has poor circulation.

For example, people with Raynaud’s disease often have very poor circulation to the fingers and sometimes the toes, leading to noticeably low skin temperature in the fingers accompanied by yellow or numb fingers when exposed to even moderately cold environments.

A person with cold hands.

People who have complications due to diabetes or peripheral neuropathy often have poor circulation to the feet and toes, leading to a low skin temperature measurement.

Even healthy adults will have a lower normal skin temperature in the extremities compared to the skin closer to the core or the skin on the forehead and around the temples.

For example, studies have found that surface skin temperature tends to be highest on the front of the neck and lowest on the sole of the foot.5Lee, C. M., Jin, S.-P., Doh, E. J., Lee, D. H., & Chung, J. H. (2019). Regional Variation of Human Skin Surface Temperature. Annals of Dermatology31(3), 349. https://doi.org/10.5021/ad.2019.31.3.349

‌You may have had a doctor check your temperature by doing a forehead skin temperature measurement rather than an ear or under-the-tongue thermometer to take your oral temperature.

This is because forehead skin thermometer readings or behind-the-ear skin thermometer readings still measure skin temperature but the normal skin temperature at these sites is not much lower than your core temperature measured by an internal thermometer reading.

Of course, if your skin is exposed to the cold, that outward-facing skin will have a lower average skin temperature than the skin covered by appropriate clothing.

A person overheated.

Moreover, the vast surface area of the skin means that this huge organ can defuse excess body heat when the core temperature rises too high, whether due to fever, exercise, or being in a hot environment.

Essentially, the skin plays a key role in thermoregulation, which is the process by which your body maintains temperature homeostasis.

By increasing blood flow to the surface of your skin, your body can help defuse excess heat energy when you are too hot.

You may notice that when exercising in the heat, your face becomes flushed, or your skin may appear rosy.

This is due to the increased cutaneous blood flow, which refers to increased circulation to the surface of your skin.

This helps activate the sweating mechanism by allowing that heat energy to evaporate the sweat moisture released onto your skin by your exocrine sweat glands and by allowing some amount of trapped body heat to be released through convection.

Therefore, you will notice that your skin temperature will be higher when you have a fever, are exercising in the heat, sitting in a sauna, or otherwise have an increased core body temperature.

A person in a sauna.

Your body is trying to get rid of excess heat energy.

The temperature of the skin can also fluctuate depending on the time of day, for example, in the evening while you sleep.

Normal skin temperature drops during sleep. As we sleep, metabolism slows down, and the body conserves energy. This will cause a decrease in body temperature.

However, in order to help bring your body temperature down before sleep, you may notice an increase in your normal body temperature between dinner and before bedtime.6https://www.facebook.com/WebMD. (2018). Slideshow: What Happens to Your Body When You Sleep? WebMD. https://www.webmd.com/sleep-disorders/ss/slideshow-sleep-body-effects

‌Here, the body starts relying on the thermal regulatory mechanisms of the skin organ to help release excess heat energy.

Therefore, some cyclical changes in normal body temperature coincide with your body’s circadian rhythm.

A person taking their temperature.

What Does High or Low Skin Temperature Mean?

There are several potential reasons why you might have a high body temperature, such as the following:

There are also several causes of low skin temperature:

  • Being exposed to cold
  • Poor circulation 
  • First part of the menstrual cycle

How Can I Accurately Measure My Skin Temperature At Home?

The best way to measure and track daily skin temperature is to use a fitness wearable such as the WHOOP strap, Oura Ring, Coros Apex 2 running watch, Polar Vantage 3 GPS running watch, or other similar high-quality fitness tracker.

These fitness and health trackers have accompanying apps where you can monitor daily fluctuations in your skin temperature as well as trends over time.

If you are concerned about your temperature range readings, contact your healthcare provider to ensure you are not experiencing any adverse medical conditions.

A sports tracker and phone.

References

Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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