These are all of the new features coming to your Apple Watch

WatchOS, the operating system that underpins the Apple Watch, is getting a major update later this year that will give early adopters a huge boost to the things they can do with their wrist, as announced at today's WWDC keynote.

For starters, Apple Watch developers will soon be able to make their own "complications," the watch industry lingo for features displayed right on the watch face, in WatchOS 2. So, in the example given by Apple's Kevin Lynch, you'll be able to see stuff like your flight times or electric car's battery level, right by looking at your wrist.

There are also new options for watch faces, including using photos from your library. You can even set it to change your watch face to a new photo from an album every time you raise your wrist. Another interesting feature is the option to use a time-lapse photo as your watch face.

Cooler still is a new feature called "Time Travel," where by rotating the Apple Watch's digital crown control on the side, you can see what's going to happen in the future - or at least the Watch's best guess. So by advancing the time with the watch, you can see what the weather will be like.

"It's a really really fun way to interact with time on your watch," Lynch says.

Apple Watch will also get a new "nightstand mode" that lets you turn it sideways and use it as an alarm clock next to your bed while it charges.

Digital touch, the system Apple Watch users can use to send each other sketched messages, will support multiple colors and a generally better drawing experience.

"Even my drawings are starting to look better with Watch OS 2," Lynch says.

In addition to your normal phone calls on the Apple Watch, it'll soon support FaceTime Audio, for "high-fidelity audio," Lynch says.

You'll also get an enhancement to Apple Pay that lets you access loyalty cards from vendors like Kohl's and Dunkin Donuts, right from the wrist, bringing Apple Watch in line with the forthcoming iOS 9.

As expected, too. Health and fitness apps can run on the native sensors. Siri can also start a workout for you, including the ability to say "Hey Siri, I want a 300 calorie bike ride," Lynch says.

Speaking of Siri, in Watch OS 2, Siri will be able to get transit directions to destinations. And Siri will also be able to "talk" to Apple HomeKit connected home devices, for things like dimming the lights. Plus, you'll be able to answer emails from your wrist by dictating to Siri.

"We think it's going to be a really, really great update to the watch," Lynch says.

WatchOS 2 is available to developers today to start building their apps, and it will be available this Fall for every Apple Watch out there as a free update.