Apple has released the first watchOS 3.1.3 developer beta for Apple Watch testers. The latest pre-release software update likely includes bug fixes and improvements.
Registered developers can access the beta by installing the Apple Watch profile from the developer center. Once installed, the software update appears in the Watch app through the Software Updates section.
Apple is also currently beta testing iOS 10.2.1, tvOS 10.1.1, and macOS 10.12.3.
watchOS 3.1.1 is the current public version of the Apple Watch operating system, although the update was temporarily pulled after issues with bricking certain hardware. While watchOS 3.1.3 is the current developer beta, a watchOS 3.1.2 update has not been released.