WatchOS 27 Fixes Siri at Last, but You May Need to Buy a New Apple Watch to Get It

Apple is finally making Siri truly useful on the wrist with WatchOS 27 — but most current Apple Watch owners will have to buy a new device to get it. The long-awaited update, announced at Apple's September keynote, brings a generative AI-powered Siri that can summarise messages, suggest replies, and execute multi-step commands entirely on-device. However, compatibility is limited to models with the S9 chip or later — effectively the Apple Watch Series 9, Ultra 2, and their successors. Older Series 8 and SE models are left out due to insufficient neural engine performance.

For years, Siri on the Apple Watch has lagged behind rival assistants on smartphones and smart speakers. Users complained of slow responses, limited offline functionality, and an inability to handle complex requests. WatchOS 27 addresses these pain points by integrating a lightweight large language model that runs locally on the Watch's Neural Engine. The new Siri can draft texts, control smart home scenes with natural language, and even provide health summaries from recent workout data — all without needing a connected iPhone.

Apple's decision to tie the feature to the S9 chip, first introduced in the Series 9 last year, means older watches lack the dedicated AI hardware required. The S9 features a quad-core Neural Engine capable of 24 trillion operations per second, nearly double the performance of the chip in the Series 8. Apple Watch models with the S8 or earlier chips simply cannot run the on-device model without unacceptable delays or battery drain, sources familiar with the matter said.

The key details of the update are clear: WatchOS 27 will be available as a free download for Apple Watch Series 9, Apple Watch Ultra 2, and all future models. It requires an iPhone XS or later running iOS 19. The update includes new Siri workflows: users can say "Get me an Uber to work and estimate arrival time" or "What did Alice say in my last five messages?" and receive near-instantaneous on-watch responses. Apple also claims privacy benefits, as all processing stays on the device — no data leaves the watch.

Analysis suggests this move is Apple’s strategic push to reinvigorate the Apple Watch upgrade cycle. After a relatively stagnant year for wearable sales, forcing Siri’s most dramatic upgrade to require new hardware is a deliberate incentive for Series 8 and SE owners to upgrade. Industry observers note that Google’s Wear OS has recently added generative AI features to the Pixel Watch, putting pressure on Apple to respond. By restricting the best Siri experience to the newest watches, Apple not only drives hardware revenue but also locks users deeper into its ecosystem.

What happens next: WatchOS 27 will enter beta in July, with a public release alongside the iPhone 17 lineup in September. Apple is expected to announce the Apple Watch Series 10 and Ultra 3 at the same event, both of which will naturally support the new Siri. For owners of older watches, the question becomes whether the long-awaited Siri upgrade is enough to justify a $399+ purchase. Early benchmarks suggest the on-device LLM reduces query latency by over 50% compared to cloud-based Siri on older models. If early adopters rave, Apple may see a surge in holiday upgrades — exactly the boost the wearable market needs.