watchOS 5.3 (build 16U6569) is an official Apple over-the-air update for the Apple Watch Series 3 (42mm, LTE), released on 2019-07-22T19:17:34Z. The update package is 85.94 MB. This is a delta (partial) update that requires 5.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 2c621adb00b7ef21a322e9eb6c82c6f5ee3a0cb6.zip.