Fenix 5 - temperature measurement

It's useless as an air thermometer while on the wrist, and there are too many variables for the watch to be able to do some math to account for body temperature and guess the air temperate any closer than the user just guessing how hot it is outside.

That said, I use it a lot, for two main things:

1) It provides a very accurate water temp reading , especially off the wrist, after about three minutes. I use this for swimming all the time.

2) When I go camping, I sleep with the watch off. I like to look at the temperature log to see how cold it got over night.

Can somebody who has a unit of F5 or F5+ family help me with understanding how the latest Fenix watches handle the presence/proximity of multiple Garmin Tempe sensors, in case they are all enabled? See https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-3/156535-

thanks a lot

Way wrong. Temperature and pressure are *directly* related. If temperature drops, pressure will also drop accordingly and vis versa. Think about how cold a pressurized canister gets as it releases the gases trapped inside: that decreased temperature is the result of decreased pressure. Kettles scream because the increased temperature results in increased pressure, thus causing the whistle as air is driven out.

So a sports example:

You are ascending a ridge from sea level to the peak at daybreak. As you ascend, pressure should drop. But if the day's temperature begins to rise throughout your ascent, pressure should therefore increase. Without measuring the temperature metric, your GPS will assume you are barely ascending, if not descending over the course of your hike. That means you can't just ignore temperature when measuring pressure changes.

While position based elevation works in most cases, it doesn't account for detailed terrain features and steep rugged terrain. Position based elevation is also only as accurate as the map it uses (in places like Alaska, maps simply lack this level if detail).If you are rockclimbing, skydiving, paragliding, or any other activities that don't remain fixed to the ground, you need barometric readings to be able to capture any useful data.

This being said, most GPS devices do allow you to override barometric altitude readings in place of position based data to avoid sudden pressure systems from skewing the data.

So how accurate is temp/baro for wrist based GPS? I'm skeptical, but so far my data looks consistent!

Without measuring the temperature metric, your GPS will assume you are barely ascending,

I hope you mean "your device that has a barometer based altitude measuring" and not GPS as in global positiion system.

GPS can measure altitude, but not very accurate. 

Barometer can "measure" altitude but will be influenced by temperature (or more general weather)

The thermometer  in a garmin watch is not very good, because it is influenced by body temperature

The barometer in a garmin watch is also not very good, imho. I've seen it make jumps which are quite impossible.

Your best bet on a more or less consistent altitude which is about in the ballpark for most users is GPS.