Smartwatches are not simple step trackers anymore. Instead, most of the latest ones allow recording blood pressure, blood oxygen level, sleep tracking, and even detecting stress using electrodermal activity such as the Fitbit Sense or the Fitbit Charge 5.
Temperature monitoring may appear as an easy add-on, but reputable brands like Apple do not offer skin temperature reading on their Apple Watch Series.
Other companies such as Fitbit can monitor temperature but only during sleep and not on an instantaneous basis. This article will go through the smartwatches that include a heat sensor and reliably detect body temperature.
Unfortunately, none of them comes with an FDA-cleared temperature sensor which may seem bizarre. No doubt that in the coming years, such a feature will be as standard as heart rate analysis, but to date, this is still a rarity in the smartwatch world.
Best for external temperature: Garmin Fenix Pro + Garmin Tempe Sensor
The Garmin Fenix 6 is probably the best outdoor activities watch money can buy. Admittedly, it comes at a premium price, but it is the Swiss army knife of Premium Multisport Watch.
Rugged and smart, the Garmin Fenix is the perfect companion when it comes to hiking and skiing. It includes a GPS with elevation but also ski maps for over 2,000 worldwide ski resorts.
When it comes to detecting the temperature, the Garmin Fenix Pro is a capable device as well. Somehow do not expect to get your body or even skin temperature. This watch is devoted to the outdoors and will measure the outside air temperature.
It is not recommended to wear the watch on your wrist when checking the temperature, as your body heat may impact the accuracy of the external air reading.
Garmin also offers numerous external devices that will connect to the watch to expand its already numerous abilities. For example, the Garmin Tempe Sensor is a digital thermometer that clips to a backpack or carabineer and connects wirelessly to the watch always to let you know the external temperature.
When skying, hiking, or even camping, this information can be helpful. Still, we certainly do not recommend investing in such a versatile and expensive device just for the sake of measuring the temperature. For those already involved in the Garmin world, the extra Garmin Tempe Sensor makes perfect sense, though, as you probably do not want to attach a $600+ watch outside of your tent or on your backpack.
Fenix Pro 6 by Garmin
Price when reviewed: From $584.99
- Very rugged. Built for the outdoor
- Off-line maps and GPS
- Plenty of updates and accessories
- The ultimate outdoor smartwatch
- Bulky and heavy
Tempe Sensor by Garmin
Price when reviewed: From $26.88
- Easy to use
- Connection may be slow
- Takes time to measure the temperature
Best for core temperature variations: Fitbit Sense
The Sense is Fitbit’s flagship watch for a reason. It has it all. The watch is a competent fitness watch and comes with many health-related features: FDA-Cleared ECG, Heart Rate, Blood Oxygen Saturation, Heart Rate Variability, Stress and Sleep Tracking, and of course, Temperature monitoring.
The only missing health-related metrics are Blood Pressure which we suspect may be coming soon. Fitbit is currently conducting clinical trials based on their Photopletysmographic sensor and the Pulse Arrival Time rationale.
The Fitbit Sense Sense and the Fitbit Versa both offer the possibility to enter the core temperature data. This is critical as most smartwatches will only record the skin temperature, which can vary depending on the outside environment you are in. Just think about getting out in winter or summer. Your skin temperature will be widely different depending on the weather. That is why we wear gloves in winter.
By entering a reference point directly into the Fitbit App, the Sense and Versa will continue monitoring your skin temperature. Still, using their algorithms, they will be able to correlate the skin temperatures variations with the core temperature ones.
This is especially useful to detect a fever or the ovulation period. The typical core temperature (temperature inside the body) vary between 97°F to 99°F (36°C to 37°C), these small differences in temperature will help in predicting ovulation (the core temperature increases slightly during the ovulation.) We somehow do not recommend only using this method for contraception. The world is filled with babies whose parents relied a bit too much on the classic “temperature method.”
Do not expect to get a precise temperature taken on the spot, as the Fitbit smartwatches will only detect the skin temperature at night while you sleep. The core temperature is at its lowest daily point during the night and represents a stable environment that helps in getting reliable results. Daily activities can also increase core temperature. One of the key purposes of sweating while exercising is to lower body temperature.
Hence measuring the temperature variation is a reliable way to detect the physiological state for ovulation or health monitoring purposes.
Sense by Fitbit
Price when reviewed: From $298.95
- Numerous health apps
- Core temperature reference
- FDA-Cleared ECG
- No built-in GPS
- Touch screen could be faster
Frontrunner for Skin temperature variations: Fitbit Charge 5
The Fitbit Charge 5 is our favorite fitness tracker for 2021. It includes all you can expect from a tracking device and many of the health-related features of the Fitbit Sense for a fraction of the price.
The Fitbit Charge 5 still misses a couple of healthcare updates, including the awaited electrocardiogram (ECG app) and the Daily Readiness Score that makes the most of the activity, heart rate variability, and sleep to compute a score that let you know if you should prioritize recovery over fitness on a daily basis.
The Fitbit Sense and the Fitbit Charge 5 will measure the skin temperature variations at night but still doesn’t allow manually entering a reference core temperature. This is a drawback in our opinion.
Anyhow, only the variations are shown, so a skin temperature variation above may signify either the ovulation period or potential infection.
For less than $200, the Fitbit Charge 5 will not only take care of your fitness level but of your health as well.
Charge 5 by Fitbit
Price when reviewed: From $178.95
- One week battery Life
- Numerous health apps
- Built-in GPS
- Some apps are still missing
- Fitbit Premium subscription needed for detailed sleep tracking
Best for price: Amazfit GTR 2e and GTS 2e
Both the Amazfit GTR 2e and GTR 2e offer the possibility of measuring skin temperature. However, the main difference between these models does not only rely on their different form factors.
The GTS has a shape that will remind of the Apple Watch Series, while the GTR with its round shape presents a more standard circular watch shape.
The GTR 2e has a battery life of up to 24 days but will lose wifi support and will rely on Bluetooth to synchronize, while the GTS 2e will only last 14 days (which is already a very long period when compared to the industry norms) but will offer the possibility of wifi transfer.
One of the specificities of both models is that the temperature is measured continuously and not only at night. This feature is unique and allows detecting temperature variations more precisely.
This can be especially useful when suffering from an infection. As with many of their competitors, the GTS and GTR 2e will detect the skin temperature and not the actual core temperature, which is not a big setback as detecting the variations over time is what really matters.
GTR 2e by Amazfit
Price when reviewed: From $139.99
- Plenty of apps
- Well priced
- Battery life shorter than expected
GTS 2e by Amazfit
Price when reviewed: From $139.99
It is now possible to find a smartwatch with a temperature sensor that will not yet measure the actual core temperature but will somehow help detect a potential infection or will help track the ovulation period.
None of these devices is FDA-cleared, and they will not replace a standard digital IR or buccal thermometer anytime soon. The Kinsa Quick Scan is our favorite digital thermometer and only costs $20. Smartwatches should be used for informational purposes only. They somehow have the potential to move one step further toward the ultimate health smartwatch.