watchOS 3.1.3 (build 14S958) is an official Apple over-the-air update for the Apple Watch Series 1 (42mm), released on 2016-12-21T18:29:58Z. The update package is 131.14 MB. This is a delta (partial) update that requires 3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: be6dda3798084ca127c533ad0cac08d3feb93eb6.zip.