watchOS 5.3 (build 16U5558b) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm), released on 2019-06-24T17:25:13Z. The update package is 160.47 MB. This is a delta (partial) update that requires 5.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6ca9664d7f2ccab9d15c7d8213872d34965e068a.zip.