The Evolution of watchOS: Exploring the Changes in Compatibility

Last week’s Worldwide Developers Conference (WWDC) keynote brought mixed news for compatibility with this year’s software updates. While iPhone users should be heartened to discover that iOS 27 will leave no iPhone behind while also delivering a nice speed boost for older models, the story for Apple Watch users wasn’t so positive.

In a nearly unprecedented move, watchOS 27 is leaving some surprisingly recent Apple Watch models stuck in the past. Although last year’s watchOS 26 release offered support as far back as the 2020 Apple Watch Series 6, this year that line is being drawn at the 2023 Apple Watch Series 9 and Apple Watch Ultra 2.

That’s two years shorter than we’d have expected. Nobody would have been surprised to see the Apple Watch Series 6 drop off the list, but nixing the Series 7, Series 8, and original Apple Watch Ultra was a shocking move. The last time Apple did this was in 2018, when it dropped the original Apple Watch from watchOS 5. That would have been a slap in the face for anyone who dropped $10K or more on the 18-karat gold Apple Watch Edition, but for many Apple Watch users it was time to upgrade anyway, as technology was moving at a much faster pace back then.

By contrast, the Apple Watch Series 8 is still a very functional device for most folks. While it’s missing the latest health monitoring features like sleep apnea detection and hypertension notifications, it still offers all the same essential fitness tracking features as newer models.

Apple’s decision to limit watchOS 27 to models released in the last three years has left many owners of the Apple Watch Series 8 and original Ultra feeling a bit disenfranchised. However, it seems Apple has its reasons, and when you really look at what’s coming in watchOS 27, it’s probably fair to say owners of older models won’t be missing much anyway — for now.

To recap, the marquee feature in this year’s watchOS release is support for Siri AI. That will undoubtedly require the more powerful chips used in the latest Apple Watch models. The Apple Watch Series 9 became the first model to support on-device Siri processing when it introduced the S9 chip as the first to include a built-in Neural Engine. At the same time, Apple used that Neural Engine to power new one-handed tap gestures, and later sleep apnea notifications in watchOS 11 and hypertension notifications in watchOS 26. Those features debuted with the Apple Watch Series 10 and Series 11, respectively, but they were available to older models going back to the Series 9.

In an interview with TechRadar’s Matt Evans, David Clark, the senior director of watchOS software engineering at Apple, and Cait Dooley, who heads up Apple Watch and Health Product marketing for the company, said the goal this year was to make the Apple Watch “a true co-partner to Apple Intelligence.”

In what’s undoubtedly the first sign of Apple’s expansion into more wearable AI technology, the Apple Watch is being positioned as a key gateway into Siri AI. Clark gave Evans the example of being able to use the Apple Watch in a grocery store to call up a list of the ingredients he needs for a particular recipe — even while his hands are full.

That sounds a bit like PR marketing-speak, and doesn’t entirely answer the question on why older Apple Watch models couldn’t have come along for the ride, even if they didn’t support all the new Siri AI features. So, Evans pointedly put that question to them, asking “exactly why so many watch users have been left high-and-dry.”

“With every software release across every single one of our platforms, we always want to ensure that you have the best experience, so we make power and performance a priority,” was Dooley’s answer, while suggesting that users of older models aren’t really missing out on anything.

While that’s not entirely true, as watchOS 27 brings some small enhancements that are unlikely to require a Neural Engine, such as the dynamic app grid, others may still be locked to the S9 chip and beyond.

For example, the new single-tap gesture joins double tap and flick as features that were introduced as exclusive features on the Apple Watch Series 9. watchOS 27 also brings new cycle deviation notifications for menopause and perimenopause, but that’s primarily a feature of the iOS 27 Health app, so it’s possible it could be available on watchOS 26, although that would still only encompass two more devices: the Apple Watch Series 8 and Apple Watch Ultra, as it requires the wrist temperature sensor introduced with those models.

For now, it appears that older Apple Watch models running watchOS 26 will continue to access the older version of Siri, even if they’re paired with an iPhone running iOS 27, although that could change by letting the iPhone do some of the heavy lifting.