Apple Watch Series 11 Overheating? WatchOS 12 Update Might Be the Culprit

When Apple announced watchOS 12 at WWDC 2025, the update promised to make the Apple Watch smarter, faster, and more intuitive than ever. As a longtime Apple Watch user—having owned every model since the Series 4—I was excited to install it on my brand-new Series 11.

But within hours of updating, I noticed something unusual. My watch, which had always run cool and efficient, was now uncomfortably warm—even when I wasn’t actively using it. At first, I assumed it was just background indexing after the update. But the heat persisted. During workouts. While charging. Even when I was just sitting at my desk.

A quick search revealed I wasn’t alone. Across Reddit, Apple’s support forums, and social media, hundreds of Series 11 owners were reporting the same issue: watchOS 12 was making their devices overheat.

How Widespread Is the Problem?

The complaints follow a consistent pattern:

• Excessive heat during normal use, particularly when running GPS, streaming music, or using third-party apps.
• Rapid battery drain, with some users losing 30-40% charge in under an hour.
• Charging interruptions, where the watch stops charging due to temperature warnings.
• Skin irritation from prolonged contact with the heated casing.

Most troubling? Nearly all reports point to watchOS 12 as the culprit. Users who downgraded to watchOS 11 (where possible) or switched to a secondary watch without the update reported no overheating issues.

What’s Causing the Overheating?

watchOS 12 introduced several major features that could be contributing to the problem:

1. Increased On-Device Processing

One of the biggest changes in watchOS 12 is the shift toward more on-device AI processing. Siri now handles many requests locally, and health algorithms (like sleep stage detection) run entirely on the watch. While this improves speed and privacy, it also means the S9 chip is working harder than ever—generating more heat in the process.

2. Background Sensor Activity

The new enhanced sleep tracking and mental health monitoring features keep sensors like the heart rate monitor and temperature sensor active for longer periods. Combined with the Always-On Display, this creates a constant low-level drain that may be pushing thermal limits.

3. Software Bugs

Some users suspect a memory leak or runaway process in watchOS 12, where certain tasks aren’t properly terminating—leading to excessive CPU usage and heat buildup. This would explain why even idle watches are overheating.

Real-World Impact: From Annoying to Concerning

For me, the overheating manifests in three key scenarios:

1. Charging: The watch becomes noticeably hot, especially with third-party chargers. Once, it paused charging altogether with a “Temperature Warning” alert.
2. Workouts: Outdoor runs with GPS and Bluetooth music cause rapid heat buildup within 10-15 minutes.
3. Sleep Tracking: Ironically, the watch now gets warm at night—precisely when it’s supposed to be gathering recovery data.

Other users report even more severe cases:

• A marathon runner had his watch shut down mid-race due to overheating.
• Several people developed skin rashes from prolonged contact with the heated underside.
• Multiple instances of battery health degradation within weeks of installing watchOS 12.

Is Apple Acknowledging the Issue?

As of now, Apple has not issued an official statement about the overheating problem. However, their support channels appear to be taking it seriously:

• Some users who contacted Apple Support were asked to submit diagnostics logs.
• A few were offered warranty replacements, suggesting Apple may be quietly addressing defective units.
• Service centers have reportedly been checking for thermal paste application issues in some Series 11 watches.

This indicates Apple is at least aware of the problem—but whether it’s a hardware flaw or a software bug remains unclear.

Temporary Fixes (While Waiting for a Patch)

If you’re dealing with overheating, these steps may help mitigate the issue:

1. Disable Always-On Display

Settings → Display & Brightness → Always On → Off
(Reduces screen-related heat generation.)

2. Limit Background App Refresh

Settings → General → Background App Refresh → Select “Off” or limit to essential apps.

3. Adjust Workout Settings

For outdoor workouts, disable unnecessary metrics like SpO2 or cadence if you don’t need them.

4. Use Only Apple-Certified Chargers

Third-party chargers—especially fast chargers—seem to exacerbate heating during charging.

5. Avoid Charging While Wearing

Let the watch cool down before putting it back on after charging.

Should You Be Worried?

Overheating isn’t just an inconvenience—it can have long-term consequences:

• Battery degradation: Excessive heat accelerates wear on lithium-ion batteries.
• Performance throttling: The watch may slow down to cool itself, affecting responsiveness.
• Potential safety risks: While rare, extreme overheating could pose a burn risk or even damage internal components.

If your watch is frequently hot to the touch, stop using it during workouts or charging until a fix is available. For more details on Apple Watch temperature management, refer to Apple’s official support document: https://support.apple.com/en-us/HT210547. This covers proper operating temperatures and safety features.

The Big Question: Software or Hardware?

There are two possibilities:

1. Software Issue: A bug in watchOS 12 is causing abnormal CPU usage or poor thermal management. If so, a future update (likely watchOS 12.1) should resolve it.
2. Hardware Issue: The Series 11’s thermals may be poorly optimized for watchOS 12’s demands. This would be harder to fix without a hardware revision.

Given that older watches (like the Series 10) running watchOS 12 aren’t overheating as severely, the problem seems tied to the Series 11’s hardware-software combination.

What Should You Do Now?

1. Monitor your watch. If overheating is occasional and mild, wait for an update.
2. Contact Apple Support if the problem is severe (frequent warnings, burns, rapid battery drain).
3. Avoid extreme temperatures. Don’t expose the watch to direct sunlight or cold shocks (like placing it in a fridge to cool down).

Final Thoughts

The Apple Watch Series 11 is a remarkable device—when it works as intended. But the watchOS 12 overheating issue undermines its reliability, especially for fitness tracking and sleep monitoring.

Apple needs to address this quickly and transparently. Whether through a software patch or a hardware recall, users shouldn’t have to choose between using their watch’s full features and risking overheating.

For now, Series 11 owners are left in limbo: excited about the future of watchOS, but frustrated by a problem that shouldn’t exist at this price point. Here’s hoping Apple turns down the heat—literally—soon.

If you’re experiencing battery drain issues with your iPhone 17 after updating to iOS 19, check out our detailed guide on how to fix fast battery drainage after iOS 19 update for proven solutions.