watchOS 3.1.3 (build 14S960) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-01-23T18:02:31Z. The update package is 137.51 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: e2528fb3a54dea1b19834e8708f4b3e64a042ffb.zip.