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Apple Watch Series 8: My Takeaways After Using It for a Month

Commentary: The temperature sensor shows promise, but I still don't know what to make of that data.

Apple Watch Series 8
The Apple Watch Series 8
James Martin/CNET

The Series 8 represents a few notable firsts for Apple's smartwatch. It's among the first to include temperature sensors, and it can also now detect car crashes -- along with the Apple Watch Ultra, cheaper SE and iPhone 14 lineup.

But none of these milestones are what stood out to me after spending a month straight wearing the Series 8. Car crash detection is a seemingly useful feature that could make the Apple Watch more vital in emergencies -- although I'm hoping most people won't have to find out. (Just maybe don't wear it on a roller coaster.) The new temperature sensors, however, are put to work almost every night when I wear my Apple Watch to sleep. The problem is that I'm still not sure what to make of that data, even after a month. 

Overall, the Series 8 doesn't feel all that different from the Series 7. In fact, it's so similar that I had a difficult time figuring out exactly what stood out the most when writing this story. But that's also very telling of the Apple Watch's evolution over the past several years. Similar to smartphones, the Apple Watch has reached the point where year-over-year upgrades aren't as exciting as they used to be. That's because the Apple Watch is in a good enough place so that you don't need the latest -- or most expensive -- model to get a great experience. Many of the Apple Watch's best new features (like low-power mode) are available via software updates for older models. 

After using the Apple Watch Series 8 consistently for one month, here's what stood out to me the most.

Temperature data is still largely a mystery

Don't think of the Apple Watch as a thermometer. Instead, the Series 8 and Ultra can passively monitor your wrist temperature overnight and log deviations from your baseline in the Apple Health app. 

While it's interesting to see how my wrist temperature compares to my baseline, the practical use cases for the Apple Watch's temperature sensors are still limited. Right now, Apple is positioning temperature sensing as being most helpful for offering retrospective ovulation estimates and improved period predictions. But if you don't ovulate or menstruate -- or do, but don't care about tracking your cycle -- the temperature sensor has little value right now. 

The graph within the Apple Health app shows that my overnight wrist temperature is pretty much always above or below its baseline. I had one of my biggest deviations on Nov. 8, when my wrist temperature dropped by almost a full degree below the norm. But I don't know why, or whether that should be a cause for concern. 

As far as I can tell, my wrist temperature readings aren't woven into any other highlights or trends within the Apple Health app. 

Screenshot of the Apple Watch Series 8's temperature data

My wrist temperature is almost never at my baseline, according to the Apple Watch Series 8.

Lisa Eadicicco/CNET

Oura, which makes an activity-tracking ring of the same name, takes a slightly different approach that I find more valuable. It uses temperature measurements as a factor in determining your readiness score. 

That score, as the name suggests, is sort of like a check-engine light for your body. It compiles data such as your resting heart rate, temperature, sleep and previous activity to determine whether you're well rested or need to take it easy. I've been wanting the Apple Watch to adopt a similar feature for a while, and the arrival of a temperature sensor in the Series 8 makes that case even stronger. 

There are a few ways Apple could make the temperature sensor more helpful in the future. The most obvious is by weaving it into other health insights, as I just mentioned. But it also has the potential to improve the Apple Watch's sleep tracking. Imagine being able to connect your Apple Watch to a HomeKit-enabled thermostat to see how deviations from your baseline correlate with the temperature in your surroundings? 

To Apple's credit, the addition of retrospective ovulation estimates shows that the company at least has a direction and purpose in mind for the Series 8's temperature sensor. Samsung, on the other hand, didn't even activate the Galaxy Watch 5's temperature sensor at launch. (It's still not functional at the time of writing).

Battery life is better than I expected, but could still use improvement

The Apple Watch Series 8 is rated for 18 hours of battery life, the same as the cheaper Apple Watch SE, last year's Series 7 and the Series 6 from 2020. I usually get about a day-and-a-half from the 45-millimeter Apple Watch with the always-on display turned on. 

The Series 8's battery life is largely the same, but there were times when I was surprised to find the battery lasting into the early evening on its second day. That was usually the case on days when I didn't track long outdoor workouts with GPS, since doing so typically drains the battery faster. However, it's also important to remember that battery life will always vary depending on factors like which settings you have enabled and which apps you're using. (I've been using the cellular model, although I haven't set up cellular connectivity). 

The Apple Watch's new low power mode, which is available on the Series 4 and later, further extends battery life. Apple says it should provide 36 hours when your iPhone is nearby, and in my anecdotal experience it largely lives up to those claims. But remember that certain functions will be limited to preserve power. The always-on display, for example, is disabled, along with background heart-rate measurements and background blood-oxygen measurements. 

While I was happy to get around two days of battery life from the Series 8 in some circumstances, the Apple Watch still falls behind Fitbit in this regard. The Fitbit Sense 2 and Versa 4 should provide up to six days of battery life, according to the company's claims. That can make it a little challenging to use the Series 8 as a consistent sleep tracker. Since you can't use it for multiple days on a single charge, that means you have to find time to charge it at least every other day. Like many people, I'm used to charging my phone overnight, so I tend to charge my watch along with it.

A screenshot of my sleep trends in the Apple Health app

My Apple Watch says I've been averaging more than 7 hours of sleep per night. Not bad!

Lisa Eadicicco/CNET

For context, I tracked my sleep 16 times on Series 8 over the course of a month. While it's not every day, it's enough to provide general insights about my overall sleeping patterns, as shown in the Trends section of the Apple Health app summary page. (I averaged about 7 hours and 11 minutes of sleep over the past 28 days, which is pretty good in my book!) 

That's great for monitoring habits over the long term, but being able to more easily track my sleep consecutively could paint an even better picture of my weekly sleeping patterns. Even though Apple was able to provide an average for my time spent asleep each night over the last seven days, that insight seems to be based on four nights of sleep data. If the Fitbit Sense 2 and Versa 4 live up to their claims, I should be able to get six nights' worth of data without having to charge my watch.

The Apple Watch's battery life is also generally in line with that of its biggest Android competitors. Samsung's Galaxy Watch 5 lasted for about 24 hours with the always-on display turned off, while the Galaxy Watch 5 Pro's bigger battery enabled it to last for 2.5 days. The Google Pixel Watch typically lasts for a day, although I've experienced slightly longer or shorter battery life depending on usage. The Apple Watch Ultra is physically larger than the 45mm Series 8 and has a higher capacity battery. But even with its larger battery, the Ultra can only last for 2.5 to 3 days when you're not tracking a lot of workouts or monitoring sleep overnight.

The larger screen is surprisingly useful

Apple Watch Series 8

The Apple Watch Series 8 has the same larger size option Apple introduced with the Series 7.

James Martin/CNET

I appreciated the bump in screen size that Apple gave the Series 7 last year, and that's no different with the Series 8. Like its predecessor, the Series 8 is available in 41mm or 45mm sizes, replacing the 40mm and 44mm options Apple offered for the Series 4 through Series 6.

It's a small change, but one that makes the Apple Watch a more capable smartphone companion. That larger screen brings a full-size QWERTY keyboard, new watch faces and additional font sizes. But it's the keyboard that stands out as being the most useful. The idea of using a miniature keyboard may sound ridiculous to some, but I find myself using it more often than I'd expected. 

Yes, dictating a response or choosing a canned reply might be easier and faster, but I like having the flexibility to craft a specific phrase without reaching for my phone. This has come in handy during walks, for example, when I don't want to reach for my phone. 

That said, the QWERTY keyboard is only ideal for sending short responses. For anything longer than a couple of words, you'll absolutely want to pull out your phone or use verbal dictation. I never thought I'd care about screen size on a smartwatch. But now that I'm spending more time out of the house than I have in the past two years, I like having a screen I can actually read comfortably when I'm on the go and don't want to take out my phone. 

The Series 8 feels like a minor improvement over the Series 7, and that's not necessarily a negative. It illustrates how far Apple's smartwatch has come over the last seven years. But at the same time, the temperature sensor's limited utility in the Series 8 also shows there's plenty of room for growth.