watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-01-09T18:13:22Z. The update package is 181.16 MB. This is a delta (partial) update that requires 4.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8dd4cc7968c481b0f0832ab55a20366781faeda2.zip.