Apple will release watchOS 27 as a free update on Monday, September 14, 2026, four days before the new Apple Watch Series 12 and Apple Watch Ultra 4 reach stores on Friday, September 18. The update runs on Apple Watch Series 9 and later, Apple Watch SE 3, and Apple Watch Ultra 2 and later.
September 14 is also the day iOS 27 arrives, and the two updates are tied together. watchOS 27 requires an iPhone 11 or later, or an iPhone SE (3rd generation), running iOS 27, so the iPhone update has to go on first.
watchOS 27 compatible Apple Watch models
Apple’s press release names three groups of watches. The Series 12 and Ultra 4 fall under the Series 9 and later and Ultra 2 and later wording, so they are covered even though they do not ship until September 18.
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| Apple Watch | watchOS 27 |
|---|---|
| Series 9, Series 10, Series 11, Series 12 | Supported |
| Apple Watch SE 3 | Supported |
| Ultra 2, Ultra 3, Ultra 4 | Supported |
| Series 8 and earlier, first-generation Ultra, earlier SE models | Not listed by Apple |
Apple has not published watchOS 27 availability beyond the models it lists, so owners of older watches should assume they are not included until Apple says otherwise. Apple has also not said whether the Apple Watch SE line gets new hardware this year; no SE was announced at the event.
Every new watchOS 27 feature
Apple’s release describes the following additions for watchOS 27.
- Siri AI with personal context, in beta, in English first. French, Japanese, Korean, Portuguese and Spanish follow in October. Not available to users under 13.
- A dynamic app grid that surfaces Siri-suggested apps.
- A single-handed tap gesture for the Smart Stack, plus Smart Stack widget suggestions.
- A new Siri Modular watch face.
- Perimenopause and menopause support in Cycle Tracking. Users 40 and over get notifications when cycle changes suggest perimenopause, and the app adds postmenopausal bleeding notifications. Not available in all regions.
- Workout Buddy works without a nearby iPhone over Wi-Fi or cellular, and adds Spanish.
Several features shown alongside the new watches are tied to the S11 chip and the new Health Sensing System rather than to watchOS 27 itself. The Readiness score, five-second heart rate sampling, and on-watch Audio Intelligence features such as Live Rewind and Siri Recap were announced for Series 12 and Ultra 4, and Apple has not said whether any of them reach older models through the software update.
What happens next
The watchOS 27 update lands on September 14. Pre-orders for Series 12, from $399, and Ultra 4, from $799, opened today, with both in stores on September 18. Our Series 12 preview covers what was expected before the keynote, and the full event recap has everything else Apple announced.
