How much data does the Apple watch use?

Your reply sounds plausible. The reality is that your thinking is off. If you have the weather on your standard watch face it is keeping itself updated so that it gives you the correct temperature whenever you look at your watch. So, if you are a person that doesn't check the weather every time you look at your phone, your data usage will be higher. Not everyone has their weather app set to maintain itself in the background on the iPhone.

Lbeachy wrote:

So, if you are a person that doesn't check the weather every time you look at your phone, your data usage will be higher. Not everyone has their weather app set to maintain itself in the background on the iPhone.

And that would fall under my statement about the having the watch causing you do to things differently than you did before.

After over a year of using my Watch, I've seen no noticeable difference in my data usage.

You won't see much difference seeing it doesn't load full apps.

The Watch itself does not use any of your data as it has no cellular capabilities. It connects to the phone via BlueTooth. Apps that you're using on the watch are getting all their information from the phone. So, in the past, in situations where you'd pull out your phone, you now look at your watch. So, unless the watch causes you do start doing radically different things than you did before (e.g, you stream more using using TuneIn because now you have the app on your watch and it's easier to control the app on your phone), you really shouldn't see any significant changes in data use.