Kerry Wan/ZDNET Follow ZDNET: Add us as a preferred source on Google. ZDNET's key takeaways Apple is slated to announce new hardware tomorrow. Notable Apple Watch updates could be coming, according to rumors. Blood pressure monitoring and sleep scores could be on the way. We're hours away from Apple's annual September hardware event, where the tech giant announces its latest releases, from iPhones and iPads to AirPods and, my favorite, Apple Watches. Also: Should you buy the iPhone 16 or iPhone 17? How to decide which model to buy Rumors are swirling about what's to come on the next generation of Apple Watches, which include the Series 11, Ultra 3, and maybe even the SE 3. Apple's latest smartwatch software, WatchOS 26, gives us a few glimpses at what the Series 11 is capable of. A new Workout Buddy feature guides Apple Watch users through their workouts with encouragement, personal record announcements, and progress reports. Apple's new Liquid Glass display makes widgets, messages, and apps appear clear on the watch and mimics the display of Apple Vision Pro headset. Outside of those software updates, I'm keeping my eyes and ears open for rumors, murmurs, and whispers on Apple's next Apple Watch. Here's what we've heard so far. 1. The full Watch lineup Rumors say we're getting not one, not two, but three Apple Watches at tomorrow's event. This includes the baseline Series 11, the rugged (and luxurious) Ultra 3, and a possible SE 3, Apple's affordable smartwatch. 2. Launch timeline Apple historically unveils its new products around the second week of September, and we expect this year's event will be no different. After the company's product announcements, we can expect a subsequent rollout and shipment of the new devices around a week or two later, as has been the case in the past. 3. Sleep scores, at last Your sleep could be getting graded soon if Apple adds sleep scores to its next Apple Watch. MacRumor's Steve Moser found a "Watch Focus Score" and Apple Watch icon with an "84" score within the code of WatchOS 26 that hints at Apple's first foray into algorithmically monitoring and ranking time spent and quality of sleep. This is one feature I've been waiting for on the Apple Watch and have enjoyed using on several other smartwatches and rings. The issue with sleep scores, I've learned through testing several sleep trackers myself, is the fact that it's not an objective datapoint and can differ based on the device. When I was testing out three wearables at once, I'd often receive three different, albeit closely related, sleep scores, which proved to me that a sleep score feature can't be totally and completely objective. Also: I took these four sleep trackers to bed. Here's which one I recommend most Because many of the health features Apple launches are backed by a bevy of clinical research or cleared by the FDA -- Apple's sleep apnea detection feature, for example -- I'm curious how a sleep score feature would look and work on the smartwatch, and how Apple will give it its own voice or twist. 4. New processor We will probably see a new processor on the Series 11 and Ultra 3, given the fact that Apple upgrades its processor with every smartwatch release. 5. Brighter display Modular Ultra watch face on the Apple Watch Ultra Jason Hiner/ZDNET The Apple Watch Series 10's peak brightness comes in at 2,000 nits. But Apple is aiming to make its next smartwatch brighter, according to serial Apple leaker Mark Gurman of Bloomberg. I've noticed that Apple's smartwatch rivals -- Google and Samsung -- have amped up their smartwatch's brightness to 3,000 nits. The Ultra 2 already has a peak brightness of 3,000 nits, so maybe the Series 11 will take that brightness as well. 6. Larger Ultra screen According to Gurman, the Apple Watch Ultra 3 gets a screen size upgrade. By how much? We don't know, but we'll find out tomorrow. 7. Satellite connectivity for Ultra 3 According to Gurman, satellite connectivity and 5G support could be coming to Apple's rugged Apple Watch Ultra 3, though they may skip the Watch 11. This could be on par with Google's recent standalone satellite feature, which doesn't require a carrier connection for off-grid communication. 8. Revamped Health app Apple has been working on giving its Health app a facelift. According to Gurman, Apple has been working on a major Health app revamp, code-named Project Mulberry, that would bring AI recommendations and actionable health and fitness insights to users. The most notable addition is an AI health coach that could "replicate, at least to some extent, a real doctor," Gurman writes. Also: 5 Apple devices you definitely shouldn't buy this month (and 7 to get instead) The health coach would use the data it collects from Apple's wearables or third-party apps to provide recommendations and insights. The AI agent is being trained using data from physicians on staff, Gurman reports. Apple has leveraged AI already for Workout Buddy, a feature that provides stats, workout metrics, and encouragement when a user logs a workout on the watch. 9. Blood pressure tracking A highly coveted feature could be implemented on the Apple Watch, but it's yet to be determined whether it's implemented in both the Series 11 and Ultra Watch 3 or one at all. Rumors about a new blood pressure sensor that allows easy monitoring without an armband are swirling. Gurman wrote that Apple was ramping up the rollout of the feature, but it seems that blood pressure monitoring has run into many hurdles. There's a chance it's not revealed this year. 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