watchOS 5.3.1 (build 16U6600) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-08-26T17:16:27Z. The update package is 82.82 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: 28bb92f55f00f5dc94b8086bdbb1c9d3ab677e74.zip.