watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-01-09T18:13:27Z. 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: 36fc3f4b6f5d83be2800f965b46e7d96d3fbcb56.zip.