watchOS 3.1.3 (build 14S6958) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2016-12-21T18:29:35Z. The update package is 50.55 MB. This is a delta (partial) update that requires 3.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4467c42789ac200c6c3ce48d4cbedc4b398933ca.zip.