Heat acclimation

It's just horrible. The idea that this should be based on the start of a ride, when you are out there for hours is so weird. And, that it totally ignores info from the device. Good grief. I have no advice, I am pissed off about this.

There also seems to be an intensity dependence. When walking in the lowest heart rate zone it does nothing , but when running up hills it does give a little something. This may also be a source of misunderstanding.

     I have another observation. Not every activity counts "Heat acclimation". In the run it does, but  for example in activity "Other", which for me, is a Calisthenics activity created by me (with GPS ON), because Garmin doesn't know it, after two hours in a hot Calisthenics park, it didn't count at all. Yoga also doesn't count because it has an inactive GPS for a change.

     So only some selected activities will count towards Heat acclimation.

gregrenwick said:

And, that it totally ignores info from the device.

You mean the temperature that the watch will measure on your wrist, while you do power runs? Or the one that it will measure while being attached to my bikes handlebars, directly in the open sun for hours?

Well, I guess it’s good, they ignore this… first will be somewhere near 36 degrees C always, second maybe even more.

Well, as I said, it was a ride. The device was on the bars, as were my hands. It was in the open sun, just like my body. The device was subjected to heat radiating from the pavement, just like I was. 

I get your point. The watch suffers from the same conditions as you.

Still, there is no way of knowing for the algorithm on the watch, if it is in the shade or in the sun. If it is on a handlebar (and cooled by wind) or on a wrist (and heated by your body).
Or to say it in short: The temperature measured by the watch is in no way objective or reliable or compareable.

Thus, they chose to go with objective data of weather stations nearby. Yeah, this has downsides, but it is kind of objective.

And I think, If the weatherstation says "30 degrees C at 11 am and sunny" and then you go for a three hours ride, the algorithm will sure give you good portion of heat acclimation.
At least it has always done to me.

By the way, this is one of the "yeah, nice to know" metrics in my opinion, but in no way meaningful to any degree for anything.
If you are interested in how the temperature affects your training, you sure will see it in the details of your HR compared to power you put in.

What I am finding out is that my watch, at least, is not displaying temperature data that agrees with any published source. It is close on current temp, but low by a degree or two. For the forecasts, it is low by 5 degrees or more. The deltas are not consistent but tend to be in the same range. This is independent of location, I have set several locations and the issue is the same for each. I checked two or three weather sources. They agreed fairly well, the watch does not. 

And, as the icing on the cake, three Garmin watches side by side did not agree. Here are two. Mine is on the left, a friend's on the right.

I wonder which sports have an effect on Heat acclimation. It seems to me that neither Walking nor Water sports affect it (also "Other" activities). It's just my feeling though, as I didn't get any after them, but whether it was underestimated temperature or the fact that the sport is not included in Heat acclimation, God knows.

P.S.: Yes, this metric is not key, but I would like to understand why things work the way they do, or why they don't work the way they should.

Unfortunately, I haven't found much relevant information on forums across other Garmin watch models either.

Either way, I'd guess it will let me go like it did last fall.