This story is part of, CNET's complete coverage from and about Apple's annual developers conference.
Apple won't be bringing WatchOS 9 to the Apple Watch Series 3, indicating the aging wearable, which was introduced in 2017, might be getting ready for retirement.
In a blog post published Monday during WWDC 2022, the company said WatchOS 9 will come as a "free software update for Apple Watch Series 4." The update will require at least an iPhone 8 or second generation iPhone SE running iOS 16 to update newer Apple Watches.
WatchOS 9 will land in autumn though Apple provided no specific date.
The new wearable operating system brings. The upgrades include Sleep Stages, which tells people how long they spent in various stages of sleep, such as REM, core and deep sleep. Medication tracking reminds people when to take their medications and provides details of how those medications might interact.
For fitness, WatchOS 9 will use the Apple Watch's accelerometer to measure vertical oscillation, or up and down movements, and use machine learning to measure stride length and ground contact time. Sensors will measure heart rate, track segments and elevation to create custom workouts. It'll also provide data to help people achieve personal bests.
For triathletes, WatchOS 9 will also automatically swap between swimming, cycling and running.