Track your nightly wrist temperature changes with Apple Watch

Apple Watch Series 8 or later, and all models of Apple Watch Ultra, can gather wrist temperature data while you sleep to help give you insight into your overall well-being.

About Wrist Temperature

Your wrist temperature is a measurement related to your body's temperature taken by your Apple Watch while you're asleep. Your body temperature naturally fluctuates and can vary each night due to your diet and exercise, alcohol consumption, sleep environment, or physiological factors such as menstrual cycles and illness. After about 5 nights, your Apple Watch will determine your baseline wrist temperature and look for nightly changes to it.

If you use Cycle Tracking, your wrist temperature can also be used to provide retrospective ovulation estimates and improve period predictions.

Here's what you need

• An Apple Watch Series 8 or later, any model of Apple Watch Ultra, or Apple Watch SE 3.

• Sleep must be set up with Track Sleep with Apple Watch enabled.

• Sleep Focus must be enabled for at least 4 hours a night for about 5 nights.

View your wrist temperature data

1. On your iPhone, open the Health app.

2. Tap Search, then tap Body Measurements.

3. Tap Wrist Temperature.

   

While your baseline is being established, you'll see "Needs More Data" at the top of your chart. Below your chart is the number of nights remaining before your wrist temperature data will be displayed as changes from your baseline. If you switch to a new Apple Watch, it takes about 5 nights to re-establish your baseline temperature.

How your wrist temperature is measured

Apple Watch Series 8 or later, all models of Apple Watch Ultra, and Apple Watch SE 3 have 2 temperature sensors—one on the back crystal, near your skin, and another just under the display. While you sleep, Apple Watch samples your temperature every five 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.

Turn off Wrist Temperature

1. On your iPhone, open the Watch app.

2. Tap Privacy.

3. Turn off Wrist Temperature.

Things you should know

• The temperature sensing feature is not a medical device and is not intended for use in medical diagnosis, treatment, or for any other medical purpose.

• The temperature sensing feature is not a thermometer and cannot provide wrist temperature measurements on-demand.

• The temperature sensing feature is designed for users who are at least 14 years old.

• Wrist temperature data can also be impacted by certain physiological, lifestyle, and environmental factors.

• To get the best results, make sure your Apple Watch fits just right. If the fit is too loose, it can impact wrist temperature data.