Apple rates the Apple Watch Ultra 4 for wear between minus 20 and 55 degrees Celsius, lists a separate 0 to 35 degree operating range, and says the 49 mm titanium case has been tested to MIL-STD 810H. It also carries an IP6X dust rating and 100 metre water resistance, and it reaches stores on Friday, September 18 from $799.
Those environmental ratings are the lines on the spec sheet that matter most on a two-day hike or a winter race, and they are also the lines Apple describes in the fewest words. Everything below comes from Apple’s tech specs and its September 9 announcement. Where a number is missing, we say so rather than fill the gap.
Key facts: what Apple publishes about the case and its ratings
| Item | What Apple publishes |
|---|---|
| Case | 49 mm Grade 5 titanium, 100 percent recycled titanium |
| Finishes | Natural titanium, black titanium |
| Size and weight | 49 x 44 x 12 mm; 63.0 g natural, 63.1 g black |
| Front crystal | Flat sapphire |
| Operating temperature | 0 to 35 C (32 to 95 F) |
| Operating temperature while worn | Minus 20 to 55 C (minus 4 to 130 F) |
| Dust | IP6X under IEC 60529 |
| Water | 100 m under ISO 22810:2010 |
| Durability testing | MIL-STD 810H |
| Price and release | From $799, in stores Friday, September 18 |
The two temperature ranges, and why they are different
Apple’s specification sheet gives two temperature figures for the Ultra 4. The first is an operating temperature of 0 to 35 C, the same wording Apple uses across its devices. The second is wider: minus 20 to 55 C while the watch is worn.
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Apple does not explain the gap between the two, and it does not say what happens at either end of the wider range. It publishes no statement about performance below minus 20 C, no warm-up behaviour, and no note on whether the display, the battery or the sensors are the limiting part.
Read plainly, the on-wrist figure is the one that describes a cold start to a race, because body heat is part of the equation. Apple has not said that in those words, so treat it as a printed range rather than a promise.
What IP6X, ISO 22810 and MIL-STD 810H each cover
The three standards Apple cites do different jobs, and none of them substitutes for another. The X in IP6X means no water rating was claimed under that standard, which is why the water resistance is quoted separately.
| Standard | What Apple attaches to it | What Apple leaves out |
|---|---|---|
| IP6X (IEC 60529) | Dust protection for the case | No water claim under this rating |
| ISO 22810:2010 | 100 m water resistance, described for swimming, snorkelling, scuba and high-speed water sports | No depth for everyday wear beyond that figure |
| EN13319 | Recreational scuba to 40 m, depth gauge accurate to plus or minus 1 m | No accuracy figure outside that depth |
| MIL-STD 810H | Apple says the watch was tested to the standard | No list of test methods, no results, no drop height |
MIL-STD 810H is the broadest of the four and the least specific in Apple’s hands. It is a United States military test standard with many separate methods covering shock, vibration, humidity and temperature, and Apple names none of the ones it ran. Our reading is that the phrase confirms testing took place and nothing more.
The case, the crystal and 63 grams on your wrist
The Ultra 4 keeps the 49 mm Grade 5 titanium case and the flat sapphire front crystal of the previous generation, in natural and black titanium. Apple lists 45 percent recycled content overall, a 100 percent recycled titanium case and a 100 percent recycled cobalt battery.
It weighs 63.0 g in natural titanium and 63.1 g in black, against 61.6 g and 61.8 g for the Ultra 3, so the new model is 1.4 g heavier by Apple’s own figures. The band fit covers wrists from 130 to 210 mm. For the smaller alternative, Apple’s Apple Watch Series 12 uses 42 mm and 46 mm cases instead.
One absence is worth noting. Apple claims a specific toughness figure for the Series 12 aluminium models, whose Ceramic Shield 2 front is described as 60 percent tougher than Ion-X glass. It publishes no equivalent number for the Ultra 4 sapphire crystal, and no scratch or crack claim of any kind.
Where the battery figures sit against all this
Apple rates the Ultra 4 at up to 50 hours of normal use, up to 84 hours in Low Power Mode, up to 18 hours of outdoor workout, up to 25 hours in Extended Workout mode and up to 45 hours in a new Max Extended Workout mode that uses one-second GPS intervals and is aimed at 100-mile races. Our arithmetic on those figures, not Apple’s: 50 hours is a little over two days and 84 hours is three and a half.
Every one of those numbers is an upper bound, and Apple attaches no temperature to any of them. It has not published a cold-weather figure, a derating curve, or a statement that the ratings hold at the bottom of the on-wrist range. The full set of hours is in our breakdown of the Apple Watch Ultra 4 announcement.
What Apple has not said
- No battery capacity in mAh, and no battery behaviour at either temperature limit.
- No MIL-STD 810H method list, no drop height and no vibration figure.
- No scratch or crack resistance claim for the sapphire crystal.
- No altitude ceiling, despite an always-on altimeter in the sensor list.
- No per-configuration prices. Apple’s shop page shows only a starting figure of $799.
Apple Watch Ultra 4 orders opened on September 9 and the watch reaches stores on Friday, September 18. watchOS 27 arrives first, on Monday, September 14, as a free update covering Ultra 2 and later, and it ships alongside the iOS 27 release the same day. Our full event recap covers everything else Apple announced on September 9.
