watchOS 3.1.3 (build 14S958) is an official Apple over-the-air update for the Apple Watch (42mm), released on 2016-12-21T18:29:45Z. The update package is 591.83 MB. This is a delta (partial) update that requires 2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b97121dd66c7cca5a36c19c171e28e0ddbb47bea.zip.