watchOS 3.1.3 (build 14S959) is an official Apple over-the-air update for the Apple Watch Series 1 (38mm), released on 2017-01-09T17:56:39Z. The update package is 137.5 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: dd4d599c5781e946bf73544a0aeac5c2b622fcfa.zip.