watchOS 4.2.2 (build 15S5540a) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2018-01-09T18:13:26Z. The update package is 47.56 MB. This is a delta (partial) update that requires 4.2.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 68448fef077eab76854a9887f9d8df7a6a67c8fc.zip.