Heat acclimatization not showing

Are you over 22C?

Yes! Some days over 30C.

Can we bump this - I don't have this showing on my Fenix 6 either - it looks like at some point this was updated because the options under pulse ox are different from what's showing on the instructional video online. Has this feature been removed?

In any case that feature is useless

Do you have the weather widget enabled? Acclimation works on FORECAST weather, not the temperature measured on the watch (which will obviously be affected by body heat).

Need to bump this up.  Six runs in two weeks, three of them between 27C to 30C. Still no heat acclimation. Prior to this I stopped running for two weeks because of a cold, since then it's not working anymore. Before I always saw heat acclimation on the watch and in GCM.

Same here, been running in 88-100 F heat and nothing. The weather widget, in general, has stopped working as well, just says "waiting on data". This is the most frustrating feature on the 945, I honestly don't think they had the bugs sorted out when they released this watch for the weather widget and it's been whack-a-mole ever since.

The weather information is obtained from the phone. I believe the GC mobile app needs location permission. Other posts in this forum have mentioned syncing before runs. Have you tried contacting Support? They can help you troubleshoot.

allow me to direct you here: https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-945/232717/weather-widget---waiting-for-data

And yes, this is something I have battled with on and off with this watch since I got it, sometimes works sometimes doesn't most of the time it doesn't.  Go see the trouble other people are having with it as well.

Well, that sucks. These types of things only get fixed if enough people open support tickets, though.