Apple Watch body temperature: How it works and where to find the data

Apple's Watch Series 8 and Watch Ultra were revealed in September 2022 and both devices come equipped with a body temperature sensor, along with a number of other key sensors, like a heart rate monitor and blood oxygen sensor.

There are two body temperature sensors on board the Apple Watch Series 8 and Watch Ultra - one on the back crystal near your skin, and another just under the display - and they both are used to enable the smartwatches to gather wrist temperature data while you are asleep to give you insight into your overall well-being.

Here's everything you need to know about what you need to get wrist temperature data from your Apple Watch and where you will find the data. 

How does wrist temperature data on Apple Watch work?

The Apple Watch Series 8 and Watch Ultra measure wrist temperature to give an indication of your body temperature. Body temperature is affected by a number of things, from diet and exercise or alcohol intake to menstrual cycles, illness and sleep environment.

In order to start gathering wrist temperature data, the Apple Watch Series 8 or Watch Ultra will need around five nights to collect measurments and determine your baseline wrist temperature. The smartwatches will then be able to determine nightly changes to that baseline. 

Apple says: "While you're sleeping, Apple Watch samples your temperature every 5 seconds. This design improves accuracy by reducing bias from the outside environment. Advanced algorithms then use this data to provide an aggregate for each night that you can view as relative changes from your established baseline temperature in the Health app."

For those who use Cycle Tracking, the Apple Watch Series 8 and Watch Ultra should be able to detect ovulation estimates and improve cycle tracking data.

How to gather wrist temperature data from Apple Watch

In order to gather wrist temperature data from Apple Watch, you'll need to have either the Apple Watch Series 8 or the Apple Watch Ultra. 

If you have either of these, you'll then need to wear your Apple Watch to bed for at least four nights and you'll need to make sure Sleep Focus is enabled with Sleep Track on.

Open the Apple Watch app for iPhone > Tap on My Watch in the bottom left > Scroll down to Sleep > Toggle on Track Sleep with Apple Watch.

How to view wrist temperature data from Apple Watch Series 8 or Watch Ultra

Once you have worn your Apple Watch to bed and tracked your sleep for at least four nights, your Apple Watch Series 8 or Watch Ultra will begin to gather your wrist temperature and monitor nightly changes. These will appear in a graph within the Health app on your iPhone.

To access your wrist temperature data and view changes, follow the steps below. It's worth mentioning that if you use cycle tracking, you should get a notification if ovulation is estimated thanks to an increase in wrist temperature.

• On your iPhone, open the Health app.
• Tap Browse, then tap Body Measurements.
• Tap Wrist Temperature.

How to turn off wrist temperature on Apple Watch

If you no longer wish to have wrist temperature tracking on, follow the steps below: 

• On your iPhone, open the Watch app.
• Tap Privacy.
• Turn off Wrist Temperature.

Source : https://www.pocket-lint.com/smartwatches/news/apple/163951-apple-watch-body-wrist-temperature-how-it-works-where-to-find-data-measurements