My Apple Watch Ultra 2 gives elevation readings that vary from day to day from about 1275 ft to slightly above 1400 ft when measurements are taken at exactly the same spot in my house. I believe (based on readings from other devices) that the actual elevation is approximately 1350 ft.
Does the "altimeter" in the AW Ultra2 vary based on barometric pressure the way the altimeter in an aircraft does or is this a bug?
It’s a GPS- and Wi-Fi-corrected barometric altimeter reading.
It wouldn’t surprise to learn it also uses the associated sensors in the paired iPhone, too.
Apple provides a calibration and calibration-reset sequence for Watch:
… Calibrate your Apple Watch for improved Workout and Activity accuracy - Apple Support
If the weather is wonky and if GPS is wonky, or probably if the iPhone is confused, the altitude shown by Watch will be wonky.
With no details from Apple, I have concluded that my Apple Watch Ultra 2 is just not up to the task of accurate altitude readings while I am trail running. In contrast, my Garmin S70 golf watch, which can also do running, is pretty accurate all the time. I run in an area with no trees and good cell service too. I do not bring my iPhone so not sure it that matters. A lot of times with the Apple watch I see "--ELEVATION" where there should be a number. Sometimes the elevation will pop back for a short time then disappear again. I think that when the algorithm gets inaccurate it stops displaying the elevation. All just guessing on my part. I did all that Apple asks to recalibrate. Also unpaired my Apple watch then re-paired it. No difference. After months of trying to resolve the problem I have given up on the Ultra 2 and use the Garmin for running because the Garmin is rock solid out on the trails.
Apple Watch Ultra2 elevation readings vary by 150 ft from day to day
