temperature is way off

The temperature graph in GC doesn't make any sense, Garmin should really just do away with it.
The only way to get a correct temp reading is by taking the watch off, otherwise it's just a mix of outside temperature and body heat.

I have found that outside it seems about 4 deg C too high at least at the end of rides/runs so although not ideal does seem to be some relationship with ambient temperature. Maybe this can be improved. Does this work any better on the F5 versions does anybody know?

Temperature is always going to be iffy with a sensor built into a device you wear on your body, even if it is just your wrist. It's really just a gimmick. Using an external sensor like the Garmin Tempe is the only way to get some sort of reliable data.

I have found that outside it seems about 4 deg C too high at least at the end of rides/runs so although not ideal does seem to be some relationship with ambient temperature. Maybe this can be improved. Does this work any better on the F5 versions does anybody know?

For a 10 or so mile hike I did yesterday, the temp recorded in GC is 66 deg F. That seems to be pretty close, but of course I don't know exactly.

I am going to throw this out there but if you want more accurate readings (during a race for example to gauge dehydration) you can add a thermo-insulating tape under the watch (between the watch and your skin). Of course I assume you would be using an HR strap since the OHR is crap during high intensity activities anyway ...

Again this is out there but someone might find it useful.
https://www.heatshieldproducts.com/automotive/heat-shield-tape-and-fasteners

Those tapes are 1.5'' wide which is pretty much the width of the 735/935 underside.

Someone mentioned on the last thread of this nature that the temp sensors is mainly there as one of the other sensors relies upon it (barometer perhaps?) rather than for an actual measurement.

For what it's worth in GC the temp on the map appears to be from a weather forecast rather than the temp sensor on the 935; that would appear to support the assertion that it's not really intended as a measuring tool.

You get the temperature on the map in GC regardless of what device you used. I think that is an actual reading at the nearest weather station at the start of your activity. It is how I largely "deduced" that, for me, the 935 settles down about 4 deg C too high - and that's also assuming that for most of my activities the start and end weather is similar.

If you pair a Tempe, you'll get more accurate temperature, as long as it's in a good spot to get the ambient temp.

The internal sensor is going to be off most of the time, as it's right on your wrist and impacted by your own body temperature. In the same way if you you wear long sleeves, it will be buffered.

If you take off the watch and put it on a table, after maybe 20 minutes, it will adjust to ambient (yes, it could take that long).

It's the same on the va-hr, f5, f5x, etc, and the only real way to get correct ambient is with a tempe. The internal sensor is used in conjunction with the baro alt, so it actually needs to know the temp inside the watch, and not the area you're in.

It happens to be about 95F today where I live, and in that case the Internal and the temps are fairly similar!

If you click on the facebook link in my sig, back in mid feb I did a post about how I use the tempe, and can clip it to about anything (basically attach it to a flat carabiner, and then you can hook it to whatever's best, like a place on your bike, a pack strap, the zipper of your jacket, etc.)

Also, if you have a tempe, I have a widget in the app store called "Temps" that displays both the internal temperature (as well as it's history graph on a second screen) and the temperature from the tempe on the same screen, so you can see the difference easily.

I have found that outside it seems about 4 deg C too high at least at the end of rides/runs so although not ideal does seem to be some relationship with ambient temperature. Maybe this can be improved. Does this work any better on the F5 versions does anybody know?

Tim - It's the same of the va-hr, f5, and f5x, and I heard it's the same from people have f3's. On the va-hr, you don't even get temperature data in the .fit unless you have a tempe due to this, and was actually a bit surprised the f5 would use the internal temp in the .fit when I first got it.