Apple

I dont know if altimeter using gps data for calculate altitude. Afaik it uses barometric pressure to calculate estimated altitude, and even slight changes in air pressure might cause the altimeter show wrong altitude

Guess what, barometric altitude determination isn’t always accurate by design.

This is one of my complaints about current Apple product features. A good number of them are either unreliable, inaccurate, or just plain don’t work. Apple needs to stop rolling out new features and fix all the glitches and things like Siri and voice to text accuracy. This has been trash for way too long.

I wonder if it’s the complication not updating correctly. What if you ask Siri what the current altitude is, does it align with what it’s says on the watch face or does it say something else?

Restart the watch.

Unpair/Pair.

Hope.

It's not designed for professional use. It will have big margins of error.

The native altimeter has been all over the place for me lately. I can recommend a free app called My Altitude, works perfectly.

I’m way more concerned about why your air quality index is so bad!

Get a real watch

Out of curiosity what is the weather doing? weather fronts can easily move an altimeter 30m.

I haven’t been able to figure out how/if the altimeter compensates for barometric pressure.

Don’t get so high next time

usually altitude is calculated from air pressure and other factors. if pressure is changing significantly over time in the same place it may result inaccuracy and inconsistent result. So if you a bit curious about altitude gain, before starting activity you could note the starting altitude as reference instead