Apple has issued the release candidate beta of watchOS 9 to Apple Watch-owning developer testers.
The newest builds can be acquired by developers taking part in the beta-testing program via the Apple Developer Center, or as an over-the-air update for devices already using beta builds. The public beta release usually arrives shortly after the developer version, and will be available through the Apple Beta Software Program website.
Beta eight takes over from the seventh, which arrived on August 23. The sixth was on August 15, the fifth from August 8, and the fourth appeared on July 28.
Final public versions of the milestone operating systems are expected to be released by the fall alongside new hardware.
The release candidate build of watchOS 9's developer beta is 20R361, replacing the seventh, 20R5359a.
WatchOS 9 introduces a number of fitness updates, including extra views within the Workout app when you turn the Digital Crown. Heart Rate Zones, a new metric, will show the intensity level of a workout.
Health adds a Medications tracker, which can remind users to take them regularly. The Sleep app is updated with new metrics for REM, Core, and Deep sleep.
Two new watch faces join the collection, Metropolitan and Playtime, with the former offering customizable numbers while the other is animated whimsy. The Astronomy face has been remastered to include cloud data from Weather, and Portraits has been enhanced with improved depth effects and tinting.
AppleInsider, and Apple itself, strongly reminds users to avoid installing the beta software on to "mission-critical" or primary devices, due to the minute chance of instability and issues that could result in the loss of data. Instead, testers should install betas onto secondary or non-essential devices, and to make sure there are sufficient backups of important data before updating.
Members of the public should stick to using the public beta releases, rather than using the developer versions.
Find any changes in the new betas? Reach out to us on Twitter at @AppleInsider or @Andrew_OSU, or send Andrew an email at andrew@AppleInsider.com.