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Apple Watch 8 body temperature sensor — here's what it could be used for

Apple Watch 7 heart rate monitor
(Image credit: Future)

Update: The Apple Watch 8 could have a boosted battery life thanks to a rumored low power mode.

The Apple Watch 8 is rumored to house a body temperature reader, potentially introducing the first new health sensor to Apple’s smartwatch in two years. 

As you may recall the Apple Watch 6 debuted blood oxygen (SpO2) measurements, but the Apple Watch 7 skipped hardware-based health upgrades.

While features like blood pressure monitoring and blood glucose monitoring for Apple Watch are believed to be years away, a skin- or body-temperature reader seems likely according to recent reports. Apple tipster Mark Gurman (opens in new tab) said in April that Apple, “is planning to add a body-temperature sensor to the watch as early as this year.”

Gurman is also convinced of new watchOS 9 features, as well as the launch of the Apple Watch SE 2 and a rugged Apple Watch designed for outdoor sports. But we’re particularly interested in the temperature sensor and what it could mean for the flagship Apple Watch 8. How will it work? Will there be a dedicated body temperature app? Can body temperature readings notify you when something might be wrong?

Of course, any discussion about the Apple Watch 8 body temperature sensor right now is speculation. Plus analyst Ming-Chi Kuo said getting the sensor's algorithm accurate enough has proved a challenge in the past.

That said, since the Apple Watch is usually the best smartwatch every year, we’re curious about how it’ll improve or expand functionality. Here’s what we know so far about the rumored Apple Watch 8 temperature reader, plus how it’ll stack up against the competition.

Apple Watch 8 body temperature sensor — what will it do?

The answer might seem obvious — the Apple Watch 8’s body temperature sensor will read your body or skin temperature, right? Maybe, but maybe not. Unlike with the heart rate and blood oxygen sensors, the Apple Watch 8 body temperature sensor might not be able to give instant readings whenever you’re wondering about your temperature. 

According to Gurman, the temperature sensor will be used to inform fertility or other expected women’s health features. Apple Health has increased efforts around women’s health recently, with the Apple Women's Health Study shedding light on PCOS and Apple Fitness Plus creating a post-pregnancy workout collection.

Research from the Department of Reproductive Endocrinology, University Hospital Zurich in Switzerland (opens in new tab) found that wrist skin temperature can detect ovulation and has a higher true-positive rate than basal body temperature. “For women interested in maximizing the chances of pregnancy, wrist skin temperature continuously measured during sleep is more sensitive than BBT for detecting ovulation,” the study concluded. 

Collecting wrist skin temperature data from the Apple Watch seems like a practical way for Apple Health to further contribute to women’s health tracking. It would easily make the Apple Watch 8 one of the best smartwatches for women. Though by not benefitting users who cannot or do not want to track fertility, the sensor’s application sounds a bit limited. 

Reading skin temperature during sleep for all users could offer a happy medium. In watchOS 8, Apple Watch sleep tracking added respiratory rate (or breathing rate) to cumulative sleep data.    

Perhaps in later watchOS updates or future versions the temperature sensors will expand to on-demand skin temperature readings or proactive notifications. For example, a higher-than-normal skin temperature could indicate illness, stress or even ailments you might not know about.

Apple Watch 8 vs. the competition

A body temperature sensor for a smartwatch or health wearable isn’t revolutionary. Some of the best fitness trackers like the Whoop 4.0 and Oura Ring Generation 3 can monitor your skin temperature as it relates to readiness and recovery. If your skin temperature is abnormally high, it might mean you’re sick or off your regular routine. The Oura Ring will even recommend taking a rest day if it recognizes a temperature change. 

Two of the best Fitbit models — the Fitbit Sense and Fitbit Charge 5 — also have skin-temperature sensors. These devices track your skin temperature overnight to see if readings differ from your personal baseline, which could be a sign of sickness or other conditions. 

Users with a Fitbit Premium subscription can see more detailed information about skin temperature variation trends, too. When comparing Apple Watch vs. Fitbit, Fitbit has a steady edge in sleep-tracking features, but skin- or body-temperature readings for Apple Watch 8 could tip the scales.

The Samsung Galaxy Watch 4 doesn’t have a skin temperature reader, but the Samsung Galaxy Watch 5 is also tipped to get skin temperature reading. Paired with potentially moving closer to FDA approval for its existing blood pressure sensor, Samsung’s smartwatch may beat the Apple Watch 8 in terms of health features.

There’s still a lot we don’t know about the Apple Watch 8, and if last year’s rumor letdown was any lesson, we need to be skeptical about third-party reports. Still, it feels like we’re due for a new health sensor in the next-gen Apple Watch — if not a body temperature reader, perhaps something else. 

Kate Kozuch is an editor at Tom’s Guide covering smartwatches, TVs and everything smart-home related. Kate also appears on Fox News to talk tech trends and runs the Tom's Guide TikTok account (opens in new tab), which you should be following. When she’s not filming tech videos, you can find her on an exercise bike, mastering the NYT Crossword or channeling her inner celebrity chef.