watchOS 5.0 (build 16R5357a) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2018-08-20T17:09:13Z. The update package is 650.35 MB. This is a delta (partial) update that requires 4.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 83e2e2ec4fb7e5c2cdfb3b516788880efca96f1d.zip.