WatchOS 4 is now available, and here's what has changed

As promised, Apple has released watchOS 4 today just in time for the release of the Apple Watch Series 3 on September 22.

The new OS offers upgrades to Heart Rate and Workout, two popular features for users who like to use their watch to monitor their health.

Here is the full change log:

Watch Faces

New Siri face that intelligently updates information based on time of day, location, and daily routines

New animated Toy Story faces featuring Woody, Buzz Lightyear, Jessie and more

New Kaleidoscope face that turns static images into symmetrical, intertwining patterns

New complications for Siri, News, Heart Rate, Now Playing, and Messages

Activity

Intelligent and personalized notifications to help you close your Activity rings each day

Monthly challenges based on the previous month's activity levels

New full screen animations to celebrate important milestones including earning an achievement and closing your rings

Replies to activity sharing notifications now include workout metrics

Workout

Redesigned app for quick starts and helpful workout type graphics

New High Intensity Interval Training (HIIT) workout with custom motion and heart rate algorithms for more accurate calorie tracking

Support for multiple workout types in one workout session

Auto sets for Pool Swim workouts with distance for each stroke type and pace for each set, automatically adjusted for rest time

Ability to automatically start a synced music playlist when you start a workout on Apple Watch Series 1 and later

Access to music controls directly in the Workout app during a workout session

Option for Do Not Disturb to be automatically turned on during workouts

Heart Rate

New visual graph showing all-day heart rate

New heart rate measurements and visual graphs for resting rate (Apple Watch Series 1 and later), walking average, workout average and high, recovery time, and sessions in the Breathe app

Option to be notified if your heart rate rises above a specified threshold while you appeared to be inactive for a 10-minute period

Current and historical details of heart rate data in the Health app on iPhone, including new Heart Rate Variability (HRV) and VO2 Max data types

Music

Redesigned app for easy scrolling through album art

Ability to sync multiple playlists for local playback with bluetooth headphones

Automatically sync curated playlists from Apple Music including Heavy Rotation, My New Music Mix, and My Favorites Mix

Other features and improvements

News app with summaries of Top Stories and save for later to read on iPhone

Flashlight and Safety Light in Control Center

Vertical scrolling through recently used apps in the Dock

App home screen available in an alphabetical list view

Mail compose and swipe gestures

Dialer pad in the Phone app

Conflicts displayed in Calendar invites

Scribble support for German

Sub-minute and repeating timers

Suggested and recent locations in Maps

Contacts and locations in smart replies