My Apple Watch Series 10 suddenly stopped recording wrist temperature

To rule out a software issue, unpairing the watch would be the next step:

Unpair and erase your Apple Watch - Apple Support

If the temperature feature still does not work as expected, you should let Apple know about the issue directly by using the Feedback link:

Feedback - Apple Watch - Apple

Contacting the official Apple Support and using the Feedback link is the only way to make Apple aware of watchOS problems, so that they can fix that in upcoming updates.

Contact Apple for support and service - Apple Support

I've had the same problem for two days. The watch stopped measuring temperature, even though I didn't change anything in the settings. I have the system updated to the latest version.

It is not a matter of the state and regulations because I live in Poland.

I did a system reset, then reconnected the watch to the phone, and set new sleep modes. What turned out to be? I had unchecked the cloning mode function from phone to watch!

Even though I didn't touch it, it must have been a system error. Check if it's still checked for you, because it's possible that the system has unchecked it. After a week of struggling with it, the watch finally measures the temperature.

Go to the "Watch" app —> General —> Focus Mode —> select clone

In sleep mode on your phone, I recommend selecting the special night watch face to make sure the mode is turned on on your watch

If it does not work consistently on both watches, this looks like a country specific watchOS issue, my Apple Watch Ultra 2 does not have this problem.

I have the same problem since 27th of Feb and after the latest update of the Apple Watch series 10. It’s frustrating as for this function I bought the watch.

Have you had them selected this whole time? „Mirror”