Why does my Apple Watch s8 stop showing temperature measuring data after 4 nights?

Hello ChrisZT,

Congratulations on your Apple Watch Series 8. Being able to track your nightly wrist temperature changes is a great feature and it can take approximately 5 nights for data to be calculated and a baseline to be established. This is an approximate and time may vary. This information is referenced briefly in the related article, specifically the section titled "How your wrist temperature is measured."

If the data doesn't calculate after approximately 5 days, you can restart your Apple Watch using the steps listed below. While a simple step, restarting is helpful in resolving many issues. You can also find these steps in the following article.

1. "If your Apple Watch is charging, take it off the charger.
2. Press and hold the side button until you see the power button  in the upper-right corner of the display.
3. Tap the power button.
4. Drag the Power Off slider.
5. After your watch turns off, press and hold the side button again until you see the Apple logo."

Restart your Apple Watch

Let us know how that goes!